Author Archives: Karin Sternberg

Life on the Edge. Ecological Dynamics of a Karoo Riverbank Nesting Aggregation.

Nesting in dense groups attracts parasites and predators, yet these aggregations persist. The very feature that seems risky creates the system’s complexity.

Karin Sternberg

For wild bees, a dry riverbed serves as a natural corridor through otherwise open terrain. Its meandering course offers landmarks to navigate by, riverbanks that shelter from the wind, scattered patches of flowers, and soils with just the right texture for burrowing.

*Tiny Bembix at its nest site on the dry riverbed*.

These conditions make it an ideal nesting habitat for species that favour sandy, well-drained ground. In the Karoo, such conditions are common along ephemeral rivers where sand wasps like Bembix dig into the sediment, and for ground-nesting bees, which constitute the majority of solitary bee species globally.

A riverbank is more than a physical feature; it’s a living record of time. Its layers mark past floods and long droughts, changes in vegetation, even ancient climates. In South West Angola, I recently stood before cliffs that revealed stories from a different era, telling of vanished seas, holding fossils of mosasaurs and plesiosaurs in their bone-beds. Here in the Karoo, there are riverbank stories that are still very much alive, written in sand and clay, and unfolding in the form of bees and their intricate communities.

At first glance, a sandy riverbank here looks unremarkable as a sheer wall of compacted earth, a few tufts of grass, roots, the odd shrub, and a scattering of stones. But come closer on a warm spring morning and the surface moves to a low, vibrating hum. Holes dot the bank like pinpricks, and from each one, bees emerge, darting into the air before disappearing again. What seems like just an eroded sandbank is, in fact, a thriving bee aggregation.

Nesting in such dense groups might seem, from an evolutionary standpoint, a bad idea. Parasites and predators quickly notice abundance. Yet these aggregations persist. The very feature that seems risky is what makes the system thrive.

A Spring Awakening

Anthophora wartmanni bees nesting in the river bank

By early September, activity on one such bank at Wolwekraal Nature Reserve is at its peak, continuing through October. It hosts a dense aggregation dominated by Anthophora wartmanni Friese — shaggy, flower-loving digger bees, large-bodied and fast-flying.

The females work tirelessly, provisioning their larvae with pollen and nectar, navigating back to the correct burrow guided by scent. Occasionally one makes a mistake, entering the wrong tunnel before backing out almost immediately, suggesting that each nest carries its own unique chemical signature.

The Anthophora may be the most conspicuous residents, but they are not alone. The same bank also supports populations of Megachile (leafcutter bees), Amegilla, Plesianthidium, and Afroanthidium species, each with slightly different nesting needs and seasonal timing.

Top row (left to right): Anthophora, Megachile, Pachyanthidium.
Bottom: Anthophora wartmanni.

Inside the bank lies a maze. Many burrows branch into two or more tunnels, a network that offers opportunity and danger in equal measure. Parasitic wasps such as the metallic cuckoo wasps (Chrysididae) and the velvet-armoured mutillids use their smaller size to slip between tunnels, entering one hole and emerging from another. The larger bees are confined to their own passages, always using the same entrance.

Nest entrance holes in the riverbank, some with several passages branching from the main tunnel.

Male bees of several species patrol the bank, flying back and forth in search of emerging females. It’s an efficient mate-location strategy and for some species seems better than waiting around at flowers, though it does mean that predators quickly learn where to find them.

The Parasites and Their Strategies

Dense nesting aggregations attract a diverse gathering of parasites and kleptoparasites, each exploiting the concentrated resource of provisioned brood cells.

Velvet Ants

Wingless female mutillid wasp, also shown here dusted with pollen after visiting a bee nest cell.

Among the most conspicuous visitors are the so-called “velvet ants” — female mutillid wasps, wingless, densely hairy, and quick-moving. They scurry over the sand in the midday heat, pausing briefly to inspect a burrow entrance before moving on. Their mission is simple but effective: find a bee’s nest, slip inside, lay an egg on the host’s larva, and leave. The developing mutillid eats the larva and its food supply. Adults, oddly enough, feed only on nectar, a dramatic dietary shift from meat to sugar that would confound most nutritionists.

A female mutillid wasp moves swiftly between the bee tunnels

Male mutillids, in contrast, keep their wings and were often seen inspecting nest entrances, probably in search of emerging females rather than hosts. This strong difference between the sexes, with winged males and wingless females, reflects how each has evolved for a different purpose: males to locate mates and females to locate hosts.

Winged males look into nest entrances, searching for emerging females

Cuckoo Wasps

Then there are the chrysidid wasps, shimmering metallic-green under the Karoo sun. The flashiest of these wasps glitter in brilliant hues of emerald, turquoise and copper. Their colours are structural — microscopic prisms in the cuticle refract light so that even a dead specimen never fades (C. Eardley, pers. comm., 30 September 2025). They slip in and out of bee tunnels, sometimes reappearing some distance away. One pair was seen mating near the bank, suggesting that for the parasites, this place serves as both hunting ground and courtship arena.

Several species of metallic-green cuckoo wasps (Chrysididae).

Cuckoo Bees

*A Coelioxys bee — a cleptoparasite that lays her eggs in the nests of other leafcutter bees.*

*A Thyreus bee — the strikingly patterned “cuckoo bee” that lays her eggs in the nests of Amegilla species.*

Cuckoo bees, including Thyreus and Coelioxys, are also regular visitors. They specialise in parasitising species like Anthophora and Amegilla. Their method differs slightly from that of the wasps: they lay their eggs in completed brood cells, leaving their larvae to consume the pollen store rather than the host larva itself. Either way, the intended offspring loses, with the host larva eventually starving.

Flies

*A parasitic bee fly (Bombyliidae) investigates a nest entrance, collecting sand to coat its eggs before flicking them into bee burrows.*

Flies join in with characteristic ingenuity. Bee flies (Bombyliidae) hover near entrances, flicking sand-coated eggs toward burrows. The sand adds weight, propelling the eggs deeper and preventing them from drying out. Once inside, the tiny larva seeks out the host’s brood and parasitises it.

Tachinid flies such as Rondanioestrus apivorus take a more direct approach: their eggs hatch almost instantly, and the larvae burrow into returning bees, developing inside their hosts. Efficiency comes in many forms.

Left: A tachinid fly (Rondanioestrus apivorus) lies in wait on the river bank, watching for returning foragers and, right, flying close to a nest entrance.

Predators and Opportunists

Ants

Ants are part of the story too. Their nests lie directly beneath the bee aggregation, and they emerge late afternoon as temperatures moderate and bee activity declines. Small ant species such as Anoplolepis steingroeveri and the larger, square-headed Tetramorium were observed carrying bee larvae from Anthophora tunnels, possibly scavenging or predating on brood cells damaged during excavation or parasitism. They were remarkably adept at transporting larvae down the steep vertical walls to their nests below. Sometimes their activity caused partial blockages in the bee tunnels, leaving some Anthophora females hovering at the entrances or trapped inside.

Among them, the Balbyter ant was also recorded. Ants likely play a dual role: as opportunistic predators on vulnerable brood and refuse removers, carrying off dead larvae and decaying provisions, like pollen. Their late-afternoon peak in activity minimises direct confrontation with actively provisioning bees.

A Balbyter ant (Camponotus fulvopilosus) pauses at the entrance of a bee burrow — part scavenger, part predator, and always alert to opportunity.

Other Hunters

A solifuge, one of the lightning-fast, spider-like sun spiders was spotted nearby. These arachnids can subdue adult bees, though they more often hunt smaller prey. Karoo scrub-robins (Cercotrichas coryphaeus) were also seen foraging along the bank, gleaning ants from the ground, bees from flowers nearby, and scanning the vertical surface for movement. It’s a reminder that vertebrates, too, are part of the system.

Shifts Through the Day

Activity at the aggregation follows the sun. At midday, when the sand is too hot for ants, bees are most active. As the sun lowers, bees retreat, ants emerge, and birds intensify their foraging. This daily rhythm allows many species to share the same narrow strip of habitat without direct competition.

Early in the morning, female bees rest on the sand, absorbing warmth before flying off. It makes them visible to predators, but in the cool Karoo mornings, it’s essential for warming their flight muscles.

A Living System

The more time I spent at this riverbank, the more its complexity unfolded. It’s a place where a diversity of species interact in patterns shaped by millions of years of coevolution. Bees emerge from countless burrows. Parasitic wasps patrol the surface. Flies hover at entrances. Ants appear and become abundant in the late afternoon. Birds scan the sides of the riverbank for movement. The aggregation exists because every element aligns perfectly: the substrate is right, the bank catches the early morning sun, and the site lies within reach of flowers. Change one variable and the system falters. That fragility is what makes biodiversity conservation so complex, and so essential. It’s not enough to save species in isolation; we must protect the very places that make their coexistence possible.

Dry riverbeds and eroded banks like this one are far more than geological features in the Karoo. They are irreplaceable threads in a vast ecological fabric. Edges where life concentrates, adapts, and thrives. In protecting these fragile corridors, we protect the processes that create diversity itself.

Aggregations as Ecological Hubs

Why do bees nest in dense groups when it attracts so many enemies?

When solitary bees nest in dense groups, they face greater risks: parasites, kleptoparasites (like Thyreus), predators, and even competition for space. From the outside, it seems counterintuitive. Why not nest alone, far from danger?

But these dense aggregations also bring key advantages, which is why they persist:

Safety in numbers: Predators and parasites become diluted across hundreds of nests. Each individual bee’s chance of being targeted decreases.
Environmental advantages: The bees tend to choose the best microhabitats — in this case, the warm, stable riverbank soils that make nesting and brood development more successful.
Social cues: Bees can locate suitable sites by following others or detecting the scent of past nesting activity, saving energy and risk in finding a new site.
Mating opportunities: Males and females find each other more easily around aggregations.
Evolutionary innovation: The close proximity of many species and individuals fosters complex ecological relationships, from parasitism to species learning how to coexist, that drive adaptation and diversity.

So, what seems risky (high predation and parasitism) is also what creates ecological richness and resilience. The “greatest risk” (clustering together) becomes the “greatest strength” (a dynamic, evolving system that sustains itself through diversity). Aggregations like this function as natural laboratories for studying coevolution, host-parasite dynamics, and community assembly. But they’re also conservation priorities. These systems depend on dynamic landscapes like seasonal flooding, bank erosion, substrate renewal. Stabilising riverbeds or preventing natural erosion eliminates the very processes that create nesting habitat. Understanding solitary bee ecology is urgent as they’re critical pollinators globally, yet far less recognised and studied than honeybees or social species. This dry riverbank, so easily overlooked, teaches us that biodiversity isn’t just about individual species. Rather, it’s about the landscapes that bring communities together and the processes that maintain them.

Stone-Hard Nests in the Karoo: Observing Megachile taraxia

Karin Sternberg

A female Megachile taraxia exiting the mud nest she is constructing on Wolwekraal.

It was spring on Wolwekraal Nature Reserve in the arid Karoo, and the bare patches of ground were alive with solitary bee activity. Besides the busy work of Tetraloniella brevikeraia—the short-horned long-horned bees—other solitary bees were active, too.

The :deflation hollow, its surface cemented by fine dust particles, was bordered by scattered stones and sparse vegetation. Several of the larger stones provided ideal nesting sites for another solitary bee, Megachile taraxia. Unlike the better-known mason bees (Osmia), which usually build in cavities, this species constructs exposed domes of mud on rock surfaces, hence its description as a mud-nesting or “dauber” bee. Until recently, M. taraxia was known only from the male and recorded at just two localities, one in Namaqualand and the other in Gauteng. Finding it here, and finding both males and females, seemed an unusual and important turn up for the books.

Stones on the edge of a deflation hollow at Wolwekraal, providing firm foundations for Megachile taraxia mud nests.

I first noticed a female sitting on a prominent stone. At a glance I thought she was resting; she had been circling me for a while with a deep buzz. Only when she alighted did I see a small wet patch. On closer inspection, I realised I was looking at a mud nest. Without that faint spot of moisture, it might have seemed no more than a chance splash of mud.

Female Megachile taraxia completing the outer seal of her mud nest using saliva.

Reading through the literature on how such mud nests are built, I came upon the works of Jean-Henri Fabre (1913) in his celebrated Souvenirs Entomologiques. He applied the name “mason bees” to those that build their cells with materials similar to our own building supplies. “It is masonry,” he wrote, “but made by a rustic workman, better used to dried clay than to hewn stone.” In his essays he describes the mud-dome nests of Chalicodoma bees. While Megachile taraxia belongs to the subgenus Pseudomegachile, Fabre’s evocative accounts of Chalicodoma nest building, with its mixing of clay, sand, and saliva into a stone-hard mortar, help to illuminate how enduring these dauber bees’ constructions can be. He writes that a calcareous clay is mixed with a little sand and kneaded with the mason’s own saliva (a mix of long-chain hydrocarbons, mainly hentriacontene and tritriacontene, produced by the labial glands). Damp spots that might make the work easier and spare her saliva, are disdained by this dauber bee, which refuses fresh earth for building, just as our builders refuse old plaster and lime. Such materials, when soaked with humidity, would not hold properly. What is needed is a dry powder that readily absorbs the disgorged saliva and, with its albuminous principles, forms a kind of Roman cement that hardens quickly, something like what we obtain with quicklime and egg white. The glandular mixture is used not only as mortar but also spread over the exterior of the nest to render it hydrophobic. The mud dome dries as rapidly as our hydraulic cements, becoming almost as hard as stone. A strong knife blade is needed to cut it. In its final form the nest scarcely recalls the original work, yet it lasts through the year without notable injury. The dome remains much as it was at the start, so solid is the masonry; only the round holes, corresponding to chambers inhabited by the larvae of the past generation, mark its surface. Such dwellings, needing only minor repairs, save much time and effort. Mason bees reuse them, and build new nests only when old ones fail.

Various stones on Wolwekraal showing Megachile taraxia mud nests, their circular openings indicating completed development and emergence. The original mud nest where the first M. taraxia female was discovered is shown top left.

Ten months after my first sighting of the female M. taraxia on her mud nest, and with the early onset of warm spring weather, the first holes appeared in the mud dome nests on Wolwekraal, marking the emergence of the next generation. Within weeks, one hole became four, and soon I began noticing many more nests I had previously overlooked, camouflaged until the perfect round openings revealed them.

Megachile taraxia males and females both utilise mud nests for resting. Top: Female resting in a nest cell (left) with close-up view (right). Bottom: Male resting in mud nest (left) with close-up detail (right).

In one abandoned hole I found a male asleep. On other occasions, I discovered females sleeping inside nests they were still constructing and provisioning. I spent several hours a day watching a female at work. She arrived with her crop full of nectar and her scopa bright yellow with pollen. Head first, she entered the mud cell to disgorge nectar. Once emptied, she backed out, turned, then reversed in to deposit pollen, brushing it from her abdomen with her hind legs. She made several trips to build up a paste-like mass of nectar and pollen, shaping it into a ball like playdough. When the provisioning was complete, she laid an egg and sealed the cell. Only then did she begin work on the next, each cell fully finished before starting another. The rock beneath her nest proved a firm and lasting foundation.

Megachile taraxia female provisioning behaviour sequence. The female arrives with her crop full of nectar and scopa laden with bright yellow pollen, enters the mud cell head-first to regurgitate nectar, then backs out, turns around, and reverses into the cell to deposit pollen.

At another location within Wolwekraal, I discovered more mud nest sites and watched both male and female M. taraxia visiting Blepharis mitrata flowers within a 50-meter radius of these nests. This dense, hard-leaved plant is locally called “scorpion bush” for its formidable spines, or “shooting seed” for its explosive seed pods when wet, and appears to be a preferred foraging resource. The males, who emerge from their mud cells first, use a smart strategy: they wait at the flowers where females come to collect pollen, which is the essential protein food for their developing larvae.

Female arriving at Blepharis mitrata to gather nectar and pollen.

By positioning themselves on or near the flowers, males dramatically improve their chances of meeting a potential mate. Between flower visits, I watched males sunbathing on rocks, stones, and patches of bare sand to warm up, often returning to the same favourite spots. Following these males actually helped me locate more nest sites, as they regularly checked mud nests, apparently monitoring for newly emerging females.

Megachile taraxia foraging and mate-seeking behavior. Left: Female with head deep in Blepharis mitrata flower collecting nectar and pollen. Right: Male basking for thermal energy while waiting for females.

Mating typically occurs either at flowers or near nest sites. Male solitary bees have developed remarkable features for finding females, including modified eyes, antennae, and legs that work like sophisticated detection equipment. Some species have even evolved enlarged brain regions that boost their vision or sense of smell, depending on whether they track down their partners by sight or scent.

Watching these bees at work left me with a sense of awe for their resilience and ingenuity. In the middle of the Karoo, on bare stones near a wind-swept deflation hollow and exposed to temperature extremes, a species so seldom recorded constructed homes almost as enduring as the stone they were built on and carried on its quiet cycle of life. To stumble upon Megachile taraxia here, in numbers and with nests so well hidden, felt like uncovering a treasure. It’s one that reminds us how much there is still to discover, and how much depends on noticing the small, stone-hard wonders at our feet.

Male Megachile taraxia emerging from a mud cell after resting overnight.

A glimpse inside the mud nest: the brood cells are lined with glandular secretions, though little is known about this aspect of bee nesting.

Field Notes from Wolwekraal:

While documenting the story of Megachile taraxia, I often found myself lying so still and so quietly that it felt as though I had become invisible to the creatures around me, or perhaps absorbed into the very terroir of the place. On several occasions, giant tortoises walked past within only a few metres, undisturbed by my presence. Once, a grey mongoose passed less than a metre away, its nearness betrayed only by the scattering of small stones shifting beneath its paws. These encounters made me feel part of the ecology of Wolwekraal, allowing me to observe not only the focal species but also other elements of the ecosystem.

A giant leopard tortoise on Wolwekraal Nature Reserve, Stigmochelys pardalis pardalis.

References:

Buchmann, S. (2023). What a Bee Knows: Exploring the Thoughts, Memories, and Personalities of Bees. Island Press.

Danforth, B. N., Hinckley, R. L., & Neff, J. L. (2019). The Solitary Bees: Biology, Evolution, Conservation. Princeton University Press.

Fabre, J. -H. (1913). Insect Life: Souvenirs of a Naturalist. MacMillan and Co., Ltd.

Keeping Bees Wild.

Rethinking bees, wildness, and what we’ve forgotten.

Karin Sternberg

Had anyone asked me 11 years ago about bees, I would have said: honeybees live in hives, they make honey, and they’re used for pollination.

That, after all, is the dominant story. The cultural idea of bees as synonymous with hives and honey is deeply ingrained, shaped by books like Maeterlinck’s The Life of the Bee, Kidd’s The Secret Life of Bees, and children’s stories like Winnie-the-Pooh. There are countless such books.

But then I found a wild honeybee nest in a rock crevice.

I lay on the ground, bees flying low over me. I could smell their comb: that rich, floral, tropical-fruit scent of fermentation as enzymes, yeasts and bacteria transformed pollen and nectar into amino acids and sugars. I felt the vibration of their wings and immersed myself in their sounds. That moment marked the beginning of my journey into the largely, and strangely, unexplored world of wild bees, astonishingly overlooked while so much attention has been given to bees in hives.

Eleven years later I am still following bees. I feel utterly privileged to be able to study wild-living honeybees and solitary bees here in South Africa. What I have seen has changed me profoundly.

It is an ecological tragedy that in Europe, where honeybees are indigenous and once nested wild in hollow trees, they now exist almost exclusively in hives. In a strange way, the stories told in those old books have become reality. The European wild honeybee has been all but lost. And in places where honeybees are not even native (the Americas, Australia, New Zealand) the vast diversity of local, indigenous bees has been overlooked, eclipsed by the familiar image of the hive.

In fact, the majority of the world’s bees live alone. They dig tunnels in the ground or find other small cavities, each species with its own remarkable nesting strategy, finely tuned to its environment. Some are so specialised that their entire life cycle is bound to a single plant, timed to emerge in perfect synchrony with its flowers.

A rare chalicodoma bee (Megachile taraxia) constructing a mud nest for her young.

My own research has taken me across varied landscapes. It began in the Cape, with its winter rainfall and ancient fynbos, a place of extraordinary botanical richness. But for the past year and a half, I have been immersed in Wolwekraal Nature Reserve, in its Prince Albert Succulent Karoo and Southern Karoo Riviere vegetation types, an arid region just 3km north of the town of Prince Albert.

You might ask: where do bees live in a desert environment?

The more than 40 species of solitary bees I’ve documented at Wolwekraal mostly nest in sparsely vegetated soil patches or in the dry river banks. But honeybees face a different challenge. There are no hollow trees here, and rock cavities are rare. The only real cavities are those dug by aardvarks. In their search for termites, aardvarks burrow into the ground, and it is these abandoned burrows that become homes for wild honeybees.

An aardvark (Orycteropus afer), with its long head, donkey-like ears, and tubular snout.

Since the end of the Karoo’s eight-year drought in 2023, honeybees have returned to the plains, building underground nests that are stunning feats of ecological adaptation.

These nests are not only homes to honeybees but also become small ecosystems. Ants, beetles, wax moths, spiders, and many smaller creatures cohabit with the bees. Honeybees are ecosystem engineers, modifying and shaping environments in ways that benefit other species. And they, too, are food for many.

Ants and honeybees share complex relationships in nature: Common harvester ants (Messor capensis) (left) haul honeybee drones into their nest while sharing the same burrow as a wild honeybee colony, while elsewhere, a Balbyter ant (Camponotus fulvopilosus) (right) carries a dead honeybee back to its nest.

The relationships between bees and plants have blown my mind. Honeybees are meticulous in their choice of flowers, seeking a diversity of pollen and nectar sources to keep their colonies healthy. The resins they gather offer microbial protection and exude essential oils. Solitary bees are just as discerning, visiting flowers not only for food, but also for building materials, scents, and other floral offerings. Some line their burrow walls with the petals of botterblom (Gazania lichtensteinii), others with the leaves of skaapertjie (Lessertia annularis). Still others use plant resin, pulp or secrete a waterproof, cellophane-like membrane. Some even mix a glandular secretion with mud. All of this ingenuity serves a single purpose: to protect their young, sealed in brood cells, sometimes for years, until the rains and the flowers return.

Botterblom (Gazania lichtensteinii) with petals neatly cut by a solitary bee to line the walls of her burrow.

A leafcutter bee (family Megachilidae) carrying a Skaapertjie leaf (Lessertia annularis) to line her burrow.

We have so much to learn from bees.

Having come to know them as wild creatures, intelligent and resourceful, finely adapted to their environments, I can no longer think of bees as simply honey-makers in boxes.

Yet our culture has normalised the idea of using bees “better.” We’ve taken them from their wild homes and stripped them of the diversity of their communities. Wild colonies, once rich in local adaptations, are reduced to pollination tools, to domesticated and managed assets under a homogenised system of beekeeping. We take their food (honey) and replace it with sugar water. (There are so many sweet alternatives to honey!) We expose them to monocultures, drench them in pesticides, and dose them with miticides and antibiotics.

In much of the world we have turned resilience into dependence.

But here in South Africa, and in places like Wolwekraal, we still have wild bees. Not only wild-living honeybees, but also a remarkable diversity of solitary bees, each uniquely adapted to place. This wildness needs fiercely protecting.

We would do far better if we looked to bees not for what we can take, but, as wild creatures, for what they can teach us and what they do to support the huge diversity of our flora.

And so would they.

Braunsapis bee on Rock Barrelwort (Euphorbia heptagona). Over 40 solitary bee species can be found on Wolwekraal Nature Reserve.

Banded Bee Pirates: Honeybee Hunters with a Sweet Tooth

How These Predatory Wasps Use Honeybees to Fuel Their Survival and Reproduction.

Karin Sternberg

Survival and reproduction come with tough choices for many animals, and both parasitic and predatory wasps—like Palarus latifrons—are no exception. They rely on two key resources: hosts or prey for their offspring, and sugar to fuel their own bodies and activities. Since these resources are often found in different locations, wasps must carefully divide their time between hunting and feeding. With short lifespans and limited or unpredictable resources, every decision counts—should they pursue prey or stop to refuel? The choice can have a significant impact on their survival and reproductive success in the wild.

Among predatory wasps, Palarus latifrons exhibits particularly striking hunting strategies, preying on honeybees (Apis mellifera), capturing them mid-flight and immediately paralysing them. Subdued bees are then carried to the wasp’s nest, where several paralysed bees are stored in a chamber. A single egg is laid on one of them. The stored prey provides nourishment for the developing larva, until it reaches the pupal stage. After pupation, the fully developed adult wasp emerges from its cocoon.

Palarus latifrons is a medium-sized solitary wasp with a robust body. The female has distinctive black and yellow bands on its abdomen, whereas the male has a black and white banded pattern and is generally smaller than the female. The thorax is usually black and their broad faces have porcelain-like markings (lati- means broad, -frons means forehead or front in Latin). Palarus latifrons is indigenous to Sub-Saharan Africa, however, its distribution extends from the Cape to as far north as Ethiopia and the Arabian deserts of mainly the Arabian Gulf countries. These wasps have adapted well to desert conditions where their activity is high in the hot and dry summer months. Its predatory behaviour has earned it the common name “Banded Bee pirate” (BBP). While it is known to target managed hives, very little has been documented about its interactions with wild honeybee nests.

Hunting for their offspring

At Wolwekraal Nature Reserve on the edge of the Great Karoo—a region considered a desert with annual rainfall less than 200 mm—3 of the 5 wild honeybee nests in deserted aardvark burrows were visited by BBPs, both female and male. One of the nests had up to 8 BBPs hunting around midday. From December through February, maximum temperatures climb to the upper 30 and low 40°C range. Ground temperatures can reach over 50°C. The BBPs use the heat of the sand to gain thermal energy, often flattening their bodies to increase surface area and maximise heat absorption. When warmed up they are capable of hunting at optimal temperature.

One of the wild honeybee nests inside an abandoned aardvark burrow.

Female Banded Bee Pirate wasp soaking up the Karoo heat on the edge of the burrow entrance.

This wasp has a formidable hunting technique. As an agile flier, the BBP is able to crisscross hive entrances of managed bee colonies, while at wild nests located in burrows, wasps dart, in swooping, circular patterns over the nest opening, sometimes diving deep into the burrow and then flying sharply upwards attempting to intercept returning foragers. Notably, no direct attacks on bees clustered on the comb at wild nests were observed.

A returning forager to her nest faces two female BBP wasps, with a male BBP nearby watching a female.

The wasp captures and subdues its prey midair, primarily targeting bees returning from foraging. However, it has also been seen persistently taunting and luring bees out of hives, striking as soon as a bee steps away from the colony. With its long, slender body, the BBP can position itself advantageously to deliver a sting. Still, honeybees sometimes manage to overpower and sting a BBP to death. Where BBP population densities are high—such as at apiary sites in the Porterville area, where we counted an average of 50 BBP wasps per hive—they can severely impact bee colonies, leading to significant honeybee losses. In a study carried out in front of a hive in the Kalahari, researchers killed 131 BBP wasps within 75min.

Female BBP wasp captures a forager with pollen still on her legs at the nest entrance.

The presence of these wasps near hives and at wild nests, is thought to induce either a ‘moaning’ sound by the bees, or a distressed ‘piping’ sound. The distress signals as recorded at the Porterville apiary site were intense and acute. Here, foraging activities halted entirely and many of the bees formed a defensive line across the hive opening, preventing BBPs from entering. At a wild nest on Wolwekraal, short, singular piping sounds were heard in the presence of the BBPs. BBP numbers were meagre and not all foraging ceased, but fewer foragers were seen leaving the nest.

BBP wasps are found in high numbers at apiary sites in hot and dry regions, drawn to a concentration of managed hives. Notice the multitude of wasps flying in front of the defensive line of honeybees in the hives. In contrast, only a few BBPs are typically observed at wild honeybee nests, where colonies are more dispersed across the landscape.

SOUNDS FROM A HIVE:

In the presence of hordes of BBP wasps, these are the distress signals emanating from a hive. Listen for the high-pitched piping sounds.

SOUNDS FROM A WILD HONEYBEE NEST:

Sounds emanating from a wild nest in the presence of a few BBP wasps. Listen closely for the short piping sounds in the background.

BBP wasps are, however, not solely dependent on having to find honeybee nests and have been seen widely dispersed. An observational study in the Tanqua Karoo, recorded BBP wasps at flowering Vachellia karroo trees and water seeps. These seepages attract a diverse array of species, including wasps, solitary bees and honeybees, especially during the hot, dry summer months. At these seeps, BBP wasps were seen carrying off honeybees. Vachellia karroo in bloom serves as a key resource attracting numerous pollinators.

Water as a limiting resource

Water is the most limiting resource for all living creatures, a challenge intensified in desert regions where resources are scarce across both time and space. Wasps require water for survival, but they do not rely solely on seepages or riverbanks to obtain it. Research on water-deprived parasitic wasps (Pachycrepoideus vindemmiae) describes a water-intake strategy whereby the researchers observed increased feeding by the wasps on the water-rich :haemolymph of their hosts, :Drosophila suzukii larvae, for nourishment, in this case, to obtain water. This led to more host (larval) mortality, because the host-feeding by the wasps to sustain themselves with water (and not just to provide food for their offspring) killed the larvae. The paper notes, that these are interesting findings, not only because water has rarely been reported as a critical nutrient for adult wasps, but especially because using prey for the purpose of hydration does not appear to be a common strategy in nature. Or is it more common than thought?

Cape cobra, belly full—likely from a rodent—slips into an abandoned aardvark burrow, once home to a wild honeybee nest. Snakes obtain much of their water from the body fluids of their prey.

The Karoo’s extreme conditions demand remarkable adaptations from its inhabitants, with resident fauna deriving most of their body water from their food. The Cape cobra (Naja nivea) meets its water needs almost entirely through the moisture derived from the body fluids and tissues of its prey. Africa’s largest rodent, the Cape porcupine (Hystrix africaeaustralis), has developed a different strategy to cope with water scarcity—digging up and consuming dwarf succulents to access their moisture. Our observations of Cape porcupine diggings on Wolwekraal revealed an intense foraging pattern. It is also speculated that the eight-year drought in the Karoo from 2015 to 2023, forced porcupines to forage on aloe stems to access both moisture and food.

Besides water for hydration, nest cooling, humidity regulation, larval nourishment, and nest building in bees and wasps, every organism requires energy to survive. Honeybees rely on a steady intake of food to fuel their daily activities—from foraging and flying, to maintaining the nest and producing honey.

Fuelling their behaviour with an energy-rich resource

Foraging demands exceptional cognitive and flight abilities, requiring high metabolic and aerodynamic power. Nectar, a sugar-rich liquid produced by the glands—or nectaries—of flowering plants, provides the necessary energy. Foraging bees collect nectar using their long proboscis (or tongue) and store it in their honey stomach before returning to the nest. Nectar typically has a high water content, usually between 50% and 80%, depending on the plant species. Honeybees process this nectar through regurgitation, enzymatic fermentation, and evaporation to produce honey. Like bees, adult wasps, require quick and significant energy for flying and hunting, which they often obtain from flower nectar or other carbohydrate sources, such as honeydew from aphids, overripe or fermenting fruit, and tree sap.

BBP wasp poised at the burrow entrance, with the comb of a wild honeybee nest visible in the background.

At Wolwekraal, BBP wasps were observed not only capturing prey at wild honeybee nests, but also fulfilling their second key requirement for survival and reproduction: obtaining sugar for energy. While the behaviour of BBP wasps extracting nectar directly from honeybees has been documented in writing, unique footage captured the extraordinary moment, providing a visual record of this fascinating interaction that, to my knowledge, has never been captured before. By preying primarily on returning foragers, these predatory wasps secure nourishment for their larvae, and access to energy-rich nectar and water. The latter is particularly vital in arid regions where water becomes scarce during the peak of summer and flowering plants are few and far between.

The BBP wasp forces open the mouthparts of the captured bee to extract nectar.

The captured bee is not always carried away to the nest but is sometimes used only as a food source. After stinging the bee, the wasp waits for it to calm down before beginning a mouth-to-mouth feeding procedure. The BBP forces open the bee’s mouthparts and, by pressing down on the bee’s abdomen, forces out the crop contents, effectively robbing it of its collected nectar. After this, the BBP either leaves the dead bee to resume hunting or, once suitably positioned, flies back to its nest with the bee. The BBP digs tunnels in the ground in especially sandy, granular soils. Inside the nest, the wasp provisions a chamber within its burrow with up to five bees, laying an egg on the mass before sealing the chamber and proceeding to provision the next one. While only females were documented exhibiting this nectar-robbing behaviour at Wolwekraal, records indicate that male BBPs also engage in this behaviour.

Slow-motion footage (50% speed) capturing the extraordinary moment a female Banded Bee Pirate wasp forces open a honeybee’s mouthparts to extract nectar—a rarely seen interaction between predator and prey.

The path back to the nest is not always easy for the BBP and its prey. In nature, especially under extreme conditions, hazards abound and opportunities must be seized. At Wolwekraal, this duo racing through the sky is often followed by a scurry of small jackal flies, flying just below the honeybee. These kleptoparasitic milichiid flies (Desmometopa spp.) feed on nutrient-rich haemolymph and are known for stealing food from other insects. They are thought to be attracted by a chemical pheromone released by the stressed honeybee and must fly rapidly to keep pace with the much larger predatory BBP.

In the Tanqua Karoo, a small aggregation of six BBP nest entrances was observed within a 20 cm × 6 cm area. Kleptoparasite flies were spotted congregating at the entrances of the BBP nests. These flies were likely Craticulina seriata, known kleptoparasites of sand wasps. They lay eggs that hatch immediately, with the larvae feeding on the honeybee prey. The observations also revealed a BBP returning to its nest, carrying a drone—the much larger male honeybee.

Kleptoparasites, *Craticulina seriata*, at the entrance to a BBP nest. Photo by Geoff Tribe.

The role of male BBP wasps at wild honeybee nests remains unclear. Like honeybee drones, males lack a sting. They often chase female wasps, possibly mating near the nest, and sometimes mistakenly pursue honeybees. This results in chaotic, fast-paced activity above the nest entrance.

The need for a balanced ecology

Observing the ecological dynamics around :wild honeybee nests offers valuable insights. The presence of large numbers of BBP wasps at apiary sites raises serious concerns. These wasps, known for their mass attacks on managed honeybee colonies, exploit the high-density clustering of hives, particularly in arid environments where resources are limited. Their predatory behaviour is intensified in these artificial settings, leading to significant colony stress, as evidenced by the increased defensive responses and distress signals from the hives. While wasps serve a critical role in ecosystem regulation, their population dynamics are highly responsive to environmental conditions, sometimes tipping the balance in their favour. This highlights the importance of conserving wild honeybees in their natural habitats, where intrinsic ecological balance helps regulate predator-prey interactions without human interference.

REFERENCES

Al-Khalaf, A. (2021). Modeling the potential distribution of the predator of honey bees, Palarus latifrons, in the Arabian deserts using Maxent and GIS. Saudi Journal of Biological Sciences 28(2).

Arena, G. And Milton, S. J. (2025). Impact of drought-induced herbivory by Cape porcupine on Aloe claviflora on the Wolwekraal Nature Reserve, Prince Albert. Journal of Arid Environments 227 (2025) 105337.

Bernstein, C. (1996). Time sharing between host searching and food searching in solitary parasitoids: state dependent optimal strategies. Behavioral Ecology 7(2):189-194.

Bezerra Da Silva, C.S., Price, B.E. and Walton, V.M. (2019). Water-Deprived Parasitic Wasps (Pachycrepoideus vindemmiae) Kill More Pupae of a Pest (Drosophila suzukii) as a Water-Intake Strategy. Sci Rep 9, 3592.

Clauss, B. (1984). The status of the Banded Bee Pirate, Palarus latifrons, as a honeybee predator in southern Africa. Paper presented at the Third International Conference of Apiculture in tropical Climates, Nairobi.

Dean, W. R. J. And Milton, S. J. (2004). The Karoo. Ecological patterns and processes. Cambridge University Press. 374 pgs.

Heiduk, A., Brake, I., Shuttleworth, A. and Johnson, S.D. (2023). ‘Bleeding’ flowers of Ceropegia gerrardii (Apocynaceae-Asclepiadoideae) mimic wounded insects to attract kleptoparasitic fly pollinators. New Phytologist 239(4).

Mally, C. W. (1908). Bee Pirates. Agricultural Journal of the Cape of Good Hope 33(2): 206-213.

Skaife, S. H.(1979). African Insect Life. Struik 279 pgs.

Tribe, G. (2021). Honey Mountain. Pinewood Studios, Cape Town. 216 pgs.

Wright, G., Nicolson, S. and Shafir, S. (2018). Nutritional Physiology and Ecology of Honey Bees. Annu. Rev. Entomol. 63:327-44.

Xylocopa io: The Rarely Seen Carpenter Bee

Karin Sternberg

Some Xylocopa have interesting adaptations, like Xylocopa io with its elongated middle legs.

A male *Xylocopa io* with a distinctively long middle leg, visible on the right of the bee.

Xylocopa bees are mostly large, robust bees. They are solitary bees, unlike honeybees that live in colonies. There are many species of carpenter bees and they are important pollinators. They excavate tunnels in dead branches which are protected from rain, and construct partitions between the individual cells, each of which is provisioned with a lump of nectar and pollen mixed together, on which a single egg is laid.

Recently while out hiking we spotted a male Xylocopa io high on a ridge between Prince Albert and the Swartberg Mountains in the Karoo. Not much is known about this species, and even less is known about the female X. io., but one interesting feature of the male is his two long middle legs.

A male *Xylocopa io* hovering, revealing its unique extra-long middle leg.

Insects are generally bilaterally symmetrical, so this male—with only one long middle leg—may have had a narrow escape from a bird, or something similar.

To attract females, Xylocopa males generally hover around a flowering shrub, then dart off, only to return seconds later to hover briefly again.

Males patrol a patch of flowers, which females visit while foraging, in order to mate with them. A patrolling male will aggressively chase away other males that intrude on his territory. The success of these encounters is enhanced by the permeation of a sex pheromone released by the male while patrolling his patch of flowers.

Male *Xylocopa caffra* on *Aspalathus capensis* (Cape capegorse).

Male *X. caffra* with less exposed membranes

Xylocopa caffra males make quick circuits over an area of several square meters. What is most fascinating is that the normally completely yellow male, when hovering around its patch of flowers, lowers its abdomen and exposes two of its interstitial membranes which appear as two black bands on the abdomen. This behavior is most likely a way for the male to release a sex pheromone, serving both as a species-specific chemical signal and as an attractant for females. When the male momentarily darts away, the membranes are less exposed compared to when he hovers.

Males of the carpenter bee Xylocopa hirsutissima have a different strategy: they fly to the top of the mountain where they spread mandibular gland secretions over the ventral surface of their abdomen while hovering in the air awaiting the female.

A rare sight: a male *Xylocopa io* with a strikingly long middle leg, a unique trait of this elusive carpenter bee.

In Xylocopa io, the male’s elongated middle legs are believed to be an adaptation for mating. During mating, the male launches into the air after the female, using his extended legs to grasp her along ridges below her three small simple eyes, known as ocelli. Interestingly, another species, Xylocopa flavrufa, exhibits a similar mating behaviour: the males also pursue females in flight, using their long middle legs for mating.

The parasitic fly, *Hyperichia bifasciata*, thought to mimic the carpenter bee *Xylocopa caffra*, .

Found in the same area as X. io, was a species of fly, Hyperichia bifasciata, known to mimic specifically Xylocopa caffra. The fly’s name, bifasciata, suggests that it may have two prominent markings or bands (the “bi-” prefix means “two” and “fasciata” refers to bands or stripes). There exists much individual variation in the colours of the bands on the thorax and abdomen, from whites to yellows. Hyperechia flies are notable for their parasitic relationship with carpenter bees. The larvae are predacious on those of Xylocopa. As adults, these flies feed on bees and wasps. H. bifasciata is not too picky and so will parasitize other Xylocopa species as well.

References:

Grünberg, K. 1907. Zur Kenntnis der Asiliden-Gattung Hyperechia Schin. (Dipt.). Deutsche Entomologische Zeitschrift: 515-524

Van Bruggen, A.C. A preliminary note on the genus Hyperechia

Schiner in Africa (Diptera: Asilidae). https://journals.co.za/doi/pdf/10.10520/AJA00128789_3712

Velthuis, H.H.W. and Camargo, J.M.F. de 1975. Further observations on the function of male territories in the carpenter bee Xylocopa (Neoxylocopa) hirsutissima Maidl (Anthophoridae, Hymenoptera. Netherlands Journal of Zoology 25(4): 516-528.

Watmough, R.H. 1974. Biology and behaviour of carpenter bees in southern Africa. The Journal of the Entomological Society of Southern Africa. 37(2): 261-281.

Far From Dead: The Surprising Biodiversity of Bare Ground

Occasionally, biodiversity might just be thriving beneath our feet.

Karin Sternberg

bare hard ground at sunset — The deflation hollow which is home to so much diversity

The resilient Karoo landscape

During my explorations of the Wolwekraal Nature Reserve, in the arid Karoo region of South Africa, a seemingly desolate stretch of land consistently caught my attention. This area, characterised by hard, ancient sediment, served as a shortcut from the jeep tracks to a wild colony of honeybees nesting in an aardvark (antbear) burrow. The flora surrounding this bare ground is a stark reminder of the Karoo’s remarkable resilience, showcasing a rich tapestry of species that thrive in one of the world’s extreme climates. Over centuries, the vegetation here has adapted to withstand dramatic temperature fluctuations, from severe winter frosts to scorching summer heat at times exceeding 50°C, often enduring prolonged periods of drought.

Yet, amid this tenacity, certain areas of the landscape remain barren and hardened. Recently, I buried a wild hare—a tragic victim of roadkill—in an aardvark dugout; a deep, empty cavity, in an area of hard ground I could never have dug myself. My sister, with her characteristic humour, had remarked, “Everyone needs an aardvark.” As I reflected on the hare’s untimely death, I was once again captivated by the number of solitary bees nesting in holes on the inner edges of these burrows. Like the wild honeybees in these landscapes, many species are dependent on the :aardvark for their nest sites; a reminder of nature’s interconnectedness. All around the dugout vibrant yellow swathes of Gazania lichtensteinii were in flower, their annual beauty enhanced by early winter rains.

Top row left to right, solitary bees living on the edge of this aardvark dugout: Samba female, Colletes female, and a Patellapis female.

Misconceptions of bare ground

The seemingly lifeless stretch of ground, a wind-scoured deflation hollow, was located close to this dugout. Deflation hollows form where vegetation is lost allowing wind to remove sandy topsoil and expose a hard subsoil comprising desert dust cemented with calcium carbonate. They are often associated with stone age human settlements of hunter-gatherers and herders. At this particular deflation hollow, there are various stone tools made from chert including a stone arrowhead. Standing on this hardened ground I was struck by a common misconception: that bare earth signifies death. Often dismissed in environmental assessments, this apparently barren, hard ground was, in fact, teeming with life and intrigue. Initially mistaking the sounds I was hearing for a drone congregation area – where honeybee males dart through the sky waiting for a queen – I quickly realised that the sound was emanating from the ground. A closer look revealed a fascinating gathering of male Tetraloniella cf. brevikeraia bees. These short-horned longhorn solitary bees were eagerly vying for a chance to mate with a female as she emerged from her underground nest. Although solitary by nature—females work alone in building nests and provisioning food—these bees form dense aggregations in favourable environments. The apparent barrenness of the ground belied its role as a prime breeding ground, and I counted an astonishing 114 nests in the vicinity.

The author documenting the diversity on the deflation hollow; it is so unassumingly rich in life (photo: Collette Hurt)

The evolutionary journey of bees

The evolutionary journey of bees, stretching back around 100 million years, began with solitary, predatory mud-dauber wasps, coinciding with the rise of flowering plants. Today, bees exhibit remarkable diversity, particularly in arid regions such as the Karoo where solitary species thrive. They range in size from a mere 2mm to 39mm and come in various forms, from densely hairy to smooth and shiny, often adorned with striking colours, masks, stripes and patterns. Most species of solitary bees prefer to nest in the ground, often using plant materials or resin to line their nests. On this hard bare ground, the thriving community of Tetraloniella served as a vivid testament to the vibrant life hidden beneath the surface.

Dynamics on the deflation hollow

The deflation hollow measured 24 m by 13 m, with nests concentrated in a mere twelve square meters. The spacing of the nests varied, with some holes nearly touching while others were separated by more than 20 cm. The solitary male bees, have one primary role: to mate. Males are remarkably specialised, with their entire existence revolving around this singular task. To prepare for mating in the earlier hours of the day with temperatures in the lower teens, the males press their bodies against the sun-warmed sand. In September, when daytime temperatures can reach 28°C, the ground can heat up to a hot 44°C. Males dart close to the surface in circular and zigzag patterns, seeking the radiated warmth that boosts their speed. I counted 26 males on this day, but their numbers waned with each subsequent day. I could only imagine how busy this aggregation had been at the beginning of mating season. Many of the males were covered in bright yellow gazania pollen from hasty sips of nectar essential for their energy needs.

A small section of the *Tetraloniella* nest aggregation

Top row: Shortly after 9 a.m., the first male Tetraloniella bees make their appearance on the deflation hollow, braving air temperatures below 15°C. Seeking warmth, they press their bodies against the sun-soaked sand, where ground temperatures already reach the mid-20s. Middle + bottom row: Males congregating around the nest holes, waiting for the females to emerge

Coexisting species: The diversity of life

In addition to the Tetraloniella bees, there were other bees thriving in this environment. Among them were various species of leafcutter, dauber and mason bees (Megachilidae) that make their nests in pre-existing burrows. Initially chased by the males, they started inspecting holes abandoned after the females emerged. These bees possess unique nesting techniques and have the broadest range of nesting behaviours. Unlike honeybees that collect pollen on their hind legs, the Megachilidae collect pollen on tufts of red hairs on the underside of their abdomen, known as a scopa. When this is fully packed with pollen it is a bright patch of colour.

Leafcutter bees construct thimble-like cells lined with leaves or petals to protect their young from moisture and predators. For their nests they were using both leaves of krimpsiektebos (Lessertia annularis) as well as gazania petals. Both of these plants contain extremely bitter compounds that possibly serve to deter parasites and provide beneficial antimicrobial properties. Another of the females (Hoplitis sp.) used chewed, reddish-pink plant pulp together with a mouth secretion to line her burrow. The source of the plant was not established but was similar in colour to bellbush (Hermannia grandiflora) flowering nearby. Similarly diverse are the materials used for plugging the entrances, with some bees choosing a combination of leaf pieces and mud, while others used mud and stones. The collected pollens for the provision of larvae with food came from plants distinct from those used for nesting materials, possibly from honeybush (Melobium candicans) or the brightfig (Rushia bijliae), both in flower and in range of the nest site and on which the bees were sighted. Each female completed one burrow per day.

Plant pulp in nesting hole of solitary bee

Megachilid bee emerging from nest burrow

Flower petal taken into hole by leaf cutting bee

Megachilid leaf cutter bee with pollen on scopa

Megachilid leaf cutter bee taking a leaf into a hole

Megachilid bees with their diverse nesting techniques, utilising burrows abandoned by Tetraloniella bees

Further careful study of the ground revealed a Camponotus rufopilosis (balbyter) ant carrying a dead conspecific. With mandibles featuring 5 to 7 teeth, these ants defend themselves by spraying formic acid when threatened. Amidst the male Tetraloniella bees, this ant dropped its prey and assumed a defensive stance. Larger, robust dauber bees (Megachile nasicornis) were also sighted, distinguished by their different, deeper sounds, and by their striking, singular patches of black and white coloration. They were also on the lookout for abandoned Tetraloniella nests to use for their own reproduction.

Balbyter ants (Camponotus rufopilosis) and the larger, more robust, dauber bees (Megachile nasicornis) on the deflation hollow

While documenting these interactions, a brown-and-white striped fly (probably in the genus Parisus) scraped her abdomen along the ground and then hovered above several bee nest holes. This Bombyliidae fly is known to parasitise a range of insects including bees. Hovering above a nest, the fly deposited 33 eggs in less than a minute. To lay eggs in this way, some Bombyliidae have a chamber near the ovipositor filled with sand which they stick to the egg, giving it enough weight to shoot deeper into the host nest and helping to prevent the egg from drying out too much. This observation might represent a new host record, and underscores the intricate relationships between host and parasite.

Top row left to right: A Bombyliid fly filling her ovipositor with sand granules, then hovering over a nest burrow to lay eggs. Bottom row left to right: A male Tetraloniella bee investigating the fly; the fly shooting an egg into the burrow (spot the egg!)

A climax

The climax of my observations came when a chaotic scrum formed around a single nest hole, where male bees gathered in a frenzied attempt to mate with the emerging virgin female. In this state where the males were fixated on the hole and seemed vulnerable to predation, I wondered if the female released a pheromone to signal her arrival. As mating commenced, the male produced a sound known as “piping,” a result of the vibrations created by the wing muscles. The male, mounted on the female, used his antennae to possibly release a volatile pheromone, engaging in a behaviour known as antennal fanning. He fans his antennae near hers without direct contact. Research indicates that a courtship pheromone may exist in bees, which is believed to induce receptiveness in the female. Clasped tightly to her, other males attempted to dislodge him, displaying a complex mating struggle. Uniquely, the female grasped a red stone during copulation, remaining mostly still amidst the chaos around her. After more than 3 minutes of mating the primary male was dislodged, and the female executed an intense spinning motion to escape, eventually flying off to establish a new nest elsewhere. (To watch the incredible mating video, click here.)

Top: A scrum of males around the hole where the female is about to emerge. Top right and middle: a tussle ensues as one male battles another for the opportunity to mate with the female. Bottom: the mating pair.

I was unable to establish the mode of excavation of the nests, or whether this species use pre-existing nest cavities as the Megachilidae do, though did note that no turrets or soil mounds were present. Similarly, I could not locate the males at night, though these are thought to form sleeping clusters hanging from a branch.

A rich tapestry of creatures

While at the study site, I encountered numerous other creatures. Among them were a rock agama, Namaqua sand lizards, cryptic Sphingonotis grasshoppers, beetles, robber flies (Asilidae), and a wingless female mutillid wasp (velvet ant). This ant-mimicking wasp was intriguing as she used her abdomen to push aside stones to enter the nest of a solitary bee—they are parasites of the larvae of ground-nesting bees. I also heard barking geckos and, with much patience, managed to photograph one in its burrow. Overhead many kinds of birds flew by, including two pale chanting goshawks. Beyond this deflation hollow, I discovered an extraordinary mud nest in the shallow of a stone; a Chalicodoma mason bee builds her nest in a hollow on a rock, sealed over by sand cemented with a secretion from her mouth.

The hidden life beneath our feet

This study illuminated a critical lesson: even the most unassuming, barren stretches of land may be far from lifeless. They may harbour intricate ecosystems, teeming with life that defies initial perceptions. The conservation of these natural nesting habitats is crucial for the survival of solitary bees and other species. Therefore, these often-overlooked spaces must be included in environmental impact assessments (EIAs). Bare ground is too rich in life to be dismissed; recognising such ecosystems is essential for maintaining biodiversity and ecological resilience, while still allowing for erosion control and restoration efforts such as reseeding rehabilitation and replanting on damaged lands or vacant erven as a means to enhance ecosystem health. Remember, biodiversity might be thriving unseen beneath our feet.

From top to bottom: Wingless female mutillid wasp (in contrast, the males can fly) entering a nest burrow of a solitary bee; Sphingonotis grasshopper and a frantic surface beetle; leafcutter bee and a pale chanting goshawk; Chalicodoma bee and a barking gecko

ACKNOWLEDGEMENTS:

Dr Sue Milton-Dean of Wolwekraal Nature Reserve

Dr Connal Eardley and Dr Michael Kuhlmann for their help with bee identifications

Dr John Mark Midgely for his assistance with fly identification and behaviour

Prof Ben-Erik van Wyk for his ID of Lessertia annularis and his extensive knowledge of plant compounds

Dr Geoff Tribe and Collette Hurt for their assistance with other species and stone artefacts

REFERENCES:

Batra, S.W.T (1984) Solitary Bees, Scientific American Vol. 250, No. 2, pp. 120-127. Scientific American, a division of Nature America, Inc., 8 pgs

Fuchs, M., Kandel, A.W., Conard, N.J., Walker, S.J. and Felix-Henningsen, P. (2008).

Geoarchaeological and Chronostratigraphical Investigations of Open-Air Sites in the Geelbek Dunes, South Africa. Geoarchaeology.

Gess, S.K. and Gess, F.W. (2014). Wasps and bees in southern Africa, SANBI Biodiversity Series 24.

Michener, C.D. (2007). The Bees of the World, The Johns Hopkins University Press.

Packer, L. (2023). Bees of the World. A Guide to Every Family, Princeton University Press.

Romani, R., Isidoro, N., Riolo, P., and Bin, F. (2003). Antennal glands in male bees: structures for sexual communication by pheromones? Apidologie 34 (2003) 603-610.

Skaife, S.H. (1963). Strange Adventures among the insects, National Boekhandel.

Slingsby, P. (2017). Ants of Southern Africa. The ant book for all, Slingsby Maps.

The nest environment as more than just a dwelling for the honeybee

Burrowing mammals actively change their environment, and provide valuable microhabitats used by other species. These burrows offer other animals vital thermal refuges from temperature extremes and environmental fluctuations particularly in hot arid and semi-arid habitats.

Karin Sternberg

The architects of the burrow

All structures have stories to tell. At Wolwekraal Nature Reserve in the arid succulent Karoo region of South Africa, three wild honeybee nests were located in aardvark burrows. Aardvarks (Orycteropus afer) are extensive burrowers in sub-Saharan ecosystems, actively modifying their environment in the construction of shelters and in excavating termitaria for food. This, in turn, generates nest sites and unique habitats that support a variety of other species, amongst them also cavity-dwelling honeybees and the numerous other creatures that co-exist in a wild nest. This article looks at the ecology of the honeybee nest site, and the dependence on the honeybee for numerous creatures as a source of food.

Honeybees are cavity dwellers

Aardvark burrow with a wild honeybee colony

Nest 1, an aardvark burrow with a colony under a sandy rim

Honeybees are cavity dwellers. At Wolwekraal trees are scarce and rock cavities are a rare sight. Dwellings, much like the food supply, are transient. Wolwekraal is situated in the Karoo Basin which once formed a deep, inland sea. Through the erosion of the mountains to its south and of the landscape towards the north, a cycle of sedimentation began. Over hundreds of millions of years layers of sediment were deposited some 3km deep, and later tilted to form the seemingly endless horizons north of the village of Prince Albert. This area supports many different and unique plants, adapting to extreme climatic conditions together with their pollinators, including the honeybee. This is also where the aardvark roams.

wild honeybee colony in aardvark burrow — Nest 2, a wild honeybee colony in an aardvark burrow

It has been suggested that the limiting factor on the number of wild honeybee colonies in any area is determined by the worst month when there is little forage. In this desert region, not only is forage challenging and limited in the hot summer months with very little other than the Vachellia karroo in flower, but also the availability of nest sites. The three wild honeybee nests located at Wolwekraal all lie along a single north flowing minor drainage line west of the Dorps river in aardvark burrows situated on deep alluvial sediments. Aardvarks avoid areas of solid or rocky ground, preferring a sandy, loose soil optimal for digging. Aardvarks are skilled burrowers, and their tunnels provide crucial thermal refuges in the extreme temperatures of the Karoo, where summer highs often exceed 40°C and rainfall is scarce. These burrows help maintain a more stable climate, with internal temperatures ranging from 25°C to 32°C, offering a respite for many species. For honeybees, whose ideal brood temperature is around 35°C, these burrows provide an ideal nesting environment. 35°C is also an ideal temperature for the moulding of wax comb by honeybees.

A small colony situated in an aardvark hole

Nest 3, a small colony situated between two aardvark diggings that are connected

The importance of shade

One of the key benefits of these aardvark burrows is the shade they provide. The relentless heat of the Karoo can make the ground scorching—often 10°C to 20°C hotter than the air. Even the sparse shade from the branches of the Vachellia karroo trees offer some relief from the heat. It is therefore not surprising to see a vast diversity of other creatures sharing the dwellings which honeybees inhabit.

Co-habitants of the nest

The scavenging Tortoise Darkling Beetle (Epiphysa flavicollis) at the edge of the honeybee colony

Termites were the first co-habitants noted in the documented nest sites. Aardvarks, in excavating these cavities, were, of course burrowing for termites upon which they feed. Over the current study period of 12 weeks, only twice did it appear as though one of the three honeybee colonies had been attacked by termites. The skirmish with the guard bees was short-lived and within a day dead termites and honeybees were removed from the nest by worker bees and dropped at distances of 20m – 50m from the colony. In environments where food is limited, it does not take long for the dead to be predated on. Immediately Pheidole and other ants arrive on the scene to carry off the bodies, as do beetles such as the Eurychora sp., commonly known as mouldy beetles. Several mouldy beetles have been documented living side-by-side with honeybees in two of the three aardvark burrows. If bees detect incursions by chemical means, it would appear as if these beetles, by covering themselves with soil and nest debris and by rubbing soil particles on each other—as documented at one of the nests—would possibly use this form of camouflage to be able to move around the periphery of the nest largely unhindered by the honeybees. Soil and vegetative debris is adhered by bristles and waxy filaments on these beetles’ backs. Mouldy beetles are detritivores, feeding on dead plant and animal litter. Such detritus is an important component of food reserves in desert regions. As such, honeybee nests offer a constant concentration of detritus to support this population. Other beetles documented in these nests include the tortoise darkling beetle (Epiphysa flavicollis) which scavenge plant and animal material at night and live for many years.

Mouldy beetles cover themselves with soil particles from their environment

A mouldy beetle feeding on organic matter close to the colony

The role of wax moths and other detritivores

Other detritus feeders are the larvae of the greater and lesser wax moth, Galleria mellonella and Achroia grisella respectively. These larvae are mostly tolerated by wild honeybees as they play an important role in maintaining nest hygiene. They help by cleaning out sections of old wax comb and are frequently found feeding on leaf litter, beeswax particles, and pollen present in the nest debris.

On the Cape Peninsula an abandoned honeybee nest in a cavity situated under rock was documented. In the nest were numerous wax moths and the deserted wax comb was writhing with wax moth larvae. In addition, two shrews made their home in the nest, benefiting from the plentiful food source provided by both the larvae and the moths. Once the larvae have cleaned the comb and both they and the shrews have departed, the nest becomes ready for re-occupation, illustrating the ingenious cycle of nature. The role of the wax moth is thought to be that of a scavenger, helping therefore to control potential diseases much like hyenas do in their ecosystems. Interestingly, the moths and the larvae continue to play a role even while the bees occupy the nest.

Shrews on the Cape Peninsula feeding on wax moth larvae

A diverse community

Skinks, too, are found feeding on wax moth in honeybee nests. In addition, the variegated skink (Trachylepis variegata) was seen feeding on small invertebrates like ants and flies. Flies abound at every honeybee nest site. Rondanioestrus apivorous, a bee tachinid, lays eggs on bees in the air as they fly into their nest. The egg almost immediately hatches into a larva which feeds on the soft tissue of the honeybee until it is ready to pupate. The bee conopid, Physocephala fascipennis with its distinctive hourglass abdomen does the same. In addition, the Blue-green bottle fly of the Lucilla sp. is also a regular visitor to the nest as are the robber flies of the family Asilidae.

The variegated skink feeds on small invertebrates like ants and flies, and is mostly tolerated by the honeybees

When a small number of Banded bee pirate wasps (Palarus latifrons) were documented at two of the three nest sites, the wasp, upon catching a returning forager flying into the entrance of the burrow, would fly off in the direction of its nest followed by a scurry of small jackal flies. These kleptoparasitic milichiid flies (Desmometopa spp.) feed on :haemolymph rich in nutrients, and they typically steal food from other insects. They are thought to be attracted by a chemical pheromone given off by the injured or stressed honeybee, and they need to be fast to keep up with the flight of the much larger predatory wasp. Banded bee pirates are most active when temperatures are between 24C and 40C. Their diet consists largely of honeybees. The wasps compete with each other for prey, each vying to catch a honeybee, darting back and forth across the nest entrance and diving at each other. The captured honeybee is stung and paralysed by the female wasp and taken to its burrow where she lays an egg on the bee. The egg hatches into a larva and consumes the bee. Other wasps, such as the Bembix wasp, have also been noted flying higher above the nest site. Bembix hunt their prey on the wing, often catching forager bees flying off or returning to the nest. Bembix typically prey on flies of various families, however not exclusively, as seen at the wild honeybee nests and where honeybees are foraging on the sweet thorn (V. karroo).

Top row: Banded bee pirate wasp carrying off a honeybee caught on the fly. Bottom row: numerous fly species wait at the nest entrance to lay eggs on returning foragers

The role of ants

Ants are so important in the ecology of a wild honeybee nest and are ever present in the nest. They are constantly contributing to nest hygiene by carrying away dead bees and other organic matter including seeds blown into the burrows. Seeds are also carried out by the bees themselves, thus both ants and honeybees are vital to seed dispersal, with ants playing a much larger role. While ants are tiny, they have a really large ecological impact. In the wild certain species may be tolerated by honeybees and we have documented ant nests side by side with wild honeybee nests, separated by a good portion of propolis. As long as there is a healthy balance, ants and bees, which are related, both being of the order Hymenoptera, coexist in close proximity, as do the termites and the honeybees at the nest site at Wolwekraal.

A balbyter ant (Camponotus rufopilosis) carrying a dead honeybee into its nest

Spiders, too, find their place within these burrows. Some spiders tunnel into the walls, and Pholcid spiders (daddy-longlegs, cellar spiders) hang upside-down in their haphazard webs. They rely more on the irregular structure of the web to trap honeybees returning to the nest, rather than it having adhesive properties. Upon detecting struggling prey these spiders swiftly wrap their prey with silk-like material, either eating it immediately or storing it for later. Jumping spiders (Salticidae) do not spin webs, but are free-running and actively stalk any prey they detect, and are often found on the soil surface. They are known to have the sharpest vision of all spiders, along with tactile chemoreceptors on their pedipalps. They mostly specialise in preying on ants which are usually plentiful, but generally prey on a wide range of insects and other spiders, and prey may sometimes include a honeybee.

Wolf spider with many babies on its back — Wolf spider with many babies on her back in a tunnel in the burrow wall

Observing nature’s complexity

The diversity in these extreme environments is surprising. So often one is reminded of the extraordinary privilege of being able to still wander in such untouched spaces; or in areas that were once farmed but have been allowed to bounce back again boasting bygone beauty. This phenomenon is particularly evident in the case of wild honeybee colonies established within burrows, where the bees thrive abundantly and do not perceive humans as threats to their resources or existence. Instead, observers are presented with the unique opportunity to engage in passive observation, immersing themselves in an alternative ecosystem characterised by intricate ecological interconnections that often transcend human comprehension. It is as if one enters a state of mindfulness previously unexplored.

A mouldy beetle (centre) and daddy-longlegs (bottom right) in a wild honeybee nest

SELECTED REFERENCES

Begg, J. (2005). A Ramble through the Rocks of the Swartberg, Prince Albert (Kweekvallei), 88-96.

Dippenaar-Schoeman A.S., Van den Berg M.A. & Van den Berg A.M. (2001). Salticid spiders in macadamia orchards in the Mpumalanga Lowveld of South Africa (Arachnida: Araneae). African Plant Protection 7(1): 47–51.

Gess, S.K.& Gess, F.W. (2014). Wasps and bees in southern Africa. SANBI Biodiversity Series 24.

Haddad, C.R. & Dippenaar-Schoeman A.S. (2002). The influence of mound structure on the diversity of spiders (Araneae) inhabiting the abandoned mounds of the snouted harvest termite Trinervitermes trinervoides (Sjöstedt). Journal of Arachnology, August 2002.

Heiduk, A., Brake, I., Shuttleworth, A. and Johnson, S.D. (2023) “‘Bleeding’ flowers of Ceropegia gerrardii (Apocynaceae-Asclepiadoideae) mimic wounded insects to attract kleptoparasitic fly pollinators,” New Phytologist.

Henschel, J. R. (2021).Long-Term Population Dynamics of Namib Desert Tenebrionid Beetles Reveal Complex Relationships to Pulse-Reserve Conditions. Insects 2021 Sep; 12(9): 804.

Hepburn, H.R. (1986). Honeybees and Wax, An Experimental Natural History. Springer Verlag, 205 pgs.

Knöthig, J. (2005). Biology of the Aardvark (Orycteropus afer). Diplomarbeit, Fakultät für Biowissenschaften der Ruprecht-Karls-Universität Heidelberg.

Milton, S. J., Short, S., & Dean, W. R. J., 2022. Decline in whistling rat (Parotomys brantsii) density: Possible response to climate change in the Karoo, South Africa. African Journal of Ecology, 60, 969–979.

Pike DA, Mitchell JC, 2013. Burrow-dwelling ecosystem engineers provide thermal refugia throughout the landscape. Animal Conservation, 16, 694–703.

Tribe, G. (2009). Creatures inside the hive, Village Life No 34, Autumn 2009.

Tribe, G. (2021). Honey Mountain. Pinewood Studios, Cape Town. 216 pgs.

Weyer, N. M. (2018). Physiological flexibility of free-living Aardvarks (Orycteropus afer) in response to environmental fluctuations. Faculty of Health Sciences, University of the Witwatersrand, Johannesburg.

About Bees, Naturally.

Karin Sternberg

Should we keep bees?

Arid to semi-arid environments are surprisingly rich in bee diversity. When most people think of bees, they often picture the honeybee (Apis mellifera). However, the reality is far more complex. Globally, there are over 23,000 bee species, the majority of which are solitary rather than social, as seen in honeybee colonies. In these solitary species, each female constructs her own nest, gathers pollen and nectar to provision her young, and lays her eggs before her brief life of sometimes just 6 to 8 weeks comes to an end. Each season often hosts its own unique bee species. This contrasts with honeybees, which remain active throughout the year in most regions of South Africa. Many of the solitary bees have co-evolved together with the flora of each region. This intricate tapestry of adaptation and survival has unfolded over millennia, leading to a remarkable diversity that thrives even in the harsh climates of areas like the Karoo. It’s astonishing to think that such diversity exists in seemingly desolate landscapes.

As I observe the bees at Wolwekraal Nature Reserve in the arid Karoo, I often feel a sense of urgency; there simply aren’t enough hours in the day to document the incredible ecology and behaviour of solitary bees currently emerging with the spring flowers. In SA we have over 1300 species of solitary bees, but many remain to be both discovered and described. So little is known about them.

Wolwekraal is a paradise for bees, but bees don’t thrive in isolation. Their presence also transforms Wolwekraal into a haven for all life that relies on them. As examples of what exists, for the past three weeks I have been engrossed in a bare patch of hardened ground surrounded by vygies, daisies, and other typical Karoo flora. Currently annuals like Gazania lichtensteinii are flowering in swathes of yellow. At first glance this sandy deflation hollow appears desolate. But I have been incredulous at the life on it! It is home to a nest aggregation of solitary bees. I counted 114 nests in just twelve square metres. The males hatch first, engaging in frantic competition to mate with the newly emerging females. Once mated, she flies off in search of a new nest site and begins her foraging for pollen and nectar to start reproducing and to ensure the survival of future generations.

The abandoned nests are then repurposed by other solitary bees, such as those in the Osmiine tribe, which includes leaf-cutting, mason, and resin bees. These female bees utilise diverse nesting techniques, often lining their burrows with remarkable reddish-pink pulp made from chewed plant material. Others use leaves and petals to construct thimble-like chambers. After foraging for nectar and pollen on flowers close by, each burrow is meticulously sealed with a mixture of sand, tiny stones or leaves, and a secretion from a special gland. Some even place stones on top for additional protection. Once her work is complete, the female dies, leaving her young to develop underground until they hatch in a year, if conditions are right.

Leaf cutter bee returning with leaf material to her nest in the ground

However, the nests are not always safe from other threats. Wingless velvet ants (a kind of wasp) are able to push out the stones and lay eggs within. Moreover, bee-flies can parasitise open nests, further complicating the lives of solitary bees. Amidst this all, balbyter ants carry off any organic debris, frantic surface beetles and sand lizards scurry by, grasshoppers leap across the terrain, and robber flies, birds and barking geckos are all in the neighbourhood.

Beyond this deflation hollow, I discovered an extraordinary mud nest in the shallow of a stone. A bee known as Chalicodoma builds her nest in a hollow in a rock sealed over by sand cemented with a secretion from her mouth. And just a short distance away, along the ancient riverbank of the Dorps, exists another active bee nesting site with a multitude of bee nests; here root and burrow fossils create extraordinary patterns between nest entrance holes. This is merely a glimpse into the myriad stories waiting to be uncovered at Wolwekraal.

Many aspects in nature remain undocumented. For example, the fly I filmed parasitising the solitary bee nests may represent a new host record. Some solitary bee species are highly specialised, acting as the sole pollinators for specific flower species. This fragile interplay highlights the delicate nature of plant-pollinator relationships. Our landscapes are vastly under-documented, and with many species facing extinction due to habitat loss and human encroachment, we must act quickly to better understand and protect these vital ecosystems.

Wild honeybees are equally fascinating, and again so little is known about them. In most places honeybees have become a commodity and are typically associated with hives (and honey), and traded as pollination units. In South Africa, fortunately, more than 90% of honeybee colonies remain wild residing in natural habitats. Contrary to common belief, we have no shortage of bees. This natural abundance fosters adaptation in micro-habitats, and to changing environments and climates. In both our solitary bees and wild honeybees, SA has a huge natural pool of excellent pollinators. In Europe, most wild honeybee populations have been lost, with the majority of western European nations seeing almost total domestication and hybridisation of their once indigenous honeybee species. As a result, many colonies succumb annually to disease and other stressors. In contrast, wild honeybees in their natural cavities create habitats conducive to survival. Their use of abundant, local, site-specific plant resins, mostly in the form of propolis, and their interactions with many other creatures, organisms and microbes within the nest, is what keeps their environment healthy.

Human activity can disrupt this delicate balance. Introducing hives to a new area can drastically alter the local ecosystem. A single hive can house up to 60,000 bees, all of which require substantial amounts of forage to thrive. The ecological consequences can be severe, especially when unaware of the existing species. Besides the risk of disease and microbial shifts, and the introduction of different strains of honeybees into an area, honeybees can outcompete solitary bees for nectar and pollen, further stressing already vulnerable populations. Wild honeybees living naturally in an area are equally affected by such increases in honeybee numbers. During periods of extreme heat or drought, wild honeybees can enter a state of dormancy, relying on stored honey to survive. It’s been suggested that the number of wild honeybee colonies in an area is limited by the worst month for forage availability.

Nature possesses a remarkable intelligence and a fragile balance that we must strive to protect. We should be cautious not to unintentionally contribute to ecological loss through changes like hive introductions in finely tuned environments. Instead, by planting indigenous flowers and veld types and allowing some areas of our gardens to remain wild, we can invite nature in and help create vibrant ecosystems. Just as Wolwekraal serves as a unique ‘laboratory’ for observing nature, our gardens can also become spaces for wild bees and other creatures, revealing the wonders of biodiversity season after season, and allowing us all to become bee-keepers of a different kind. Who knows what bees we may yet discover.

Honeybees and Gomphocarpus filiformis (lammerlat): A source of propolis in the Great Karoo

Karin Sternberg

Karoo landscape with Lammerlat (Gomphocarpus filiformis)

Wild honeybees and propolis

The wild honeybees of Southern Africa are renowned for their propensity in the use of propolis which enhances their survival in the wild. The vast amount of propolis collected and deposited in and around a wild colony attests to its value to the honeybees. But where do the bees collect the waxes, resins and plant exudates that form the basis of propolis, and in such large amounts? Individual honeybees are occasionally seen scraping waxes from buds of Protea species or resin oozing from a wound on the trunks of Vachellia karroo, but most sources of propolis are largely unknown. Although the topography and hence plant species composition may vary greatly between regions, the honeybees appear to have little difficulty in locating a source.

Recorded here is an observation of honeybees collecting the exudate from an oviposition puncture caused by a tephritid fruitfly whose larvae feed on the seeds of a plant widespread in the Karoo.

Extensive use of propolis in a wild honeybee nest — The extensive use of propolis in a wild honeybee nest.

Lammerlat (Gomphocarpus filiformis)

Gomphocarpus filiformis, a plant commonly known as lammerlat (an Afrikaans word, lammer = lambs, lat = stick, often used as a stick to chivy lambs when herding), is widespread across Namibia and the western arid interior of South Africa primarily in Desert, Nama-Karoo and Succulent Karoo habitats. Honeybees were first documented on lammerlat early in December 2023 at KRAAL, a garden in the Prince Albert municipality, where they were collecting resins on horn-like seed pods. The horns indicate that it belongs to the Asclepiadaceae into which family the stapeliads are prominent. There is a fruitfly species which lays its eggs in the stapelia pods where the fly larvae consume the seeds as they develop. A limited survey showed that 98% of the seeds on several Hoodia gordonii plants were entirely consumed (G. Tribe, unpub.). Was this happening on the horn-like seed pods of lammerlat?

Gomphocarpus filiformis (lammerlat), is found primarily in arid habitats.

A honeybee collecting resins on a seedpod of Gomphocarpus filiformis (lammerlat).

Adaptive significance of plant resins and cardiac glycosides in defense and medicinal contexts

Resins are a defensive mechanism of plants and have a physical function (expelling an organism or encasing it) and a chemical antibiotic function (especially for fungi but also insects). For especially mammalian predators, there are heart poisons called cardiac glycosides (also in Erythrina seeds), hydrogen cyanide, etc. Yet porcupines feed without consequence on a wide variety of poisonous bulbs that are deadly to other animals. Nomadic peoples eat locusts or saturniid caterpillars by first removing the guts for they may contain poisonous plant material. Fireflies make cardiac glycosides and they have evolved warning colouration. Toads also possess such compounds. In very small doses these cardiac glycosides may stimulate the heart and are thus used in the treatment of congestive heart failure and arrhythmia, but at higher doses can cause havoc and death.

When injured, lammerlat oozes a milky sap-like resin, a latex, as a defensive response against pathogens. This sap contains cardiac glycosides that are likewise toxic to herbivorous animals. But some insects, like the monarch butterfly and locusts, incorporate it as a defence mechanism and thus become toxic to their predators (S. Milton-Dean, pers. com., Dec. 2023). Thus a defence strategy evolved by a plant to avoid being eaten can be co-opted by another organism so that it too can avoid being eaten. Most early medicines used by humans involved the same principle in plant-based medication when taken at the correct dosage rate.

Honeybee collecting milkweed resins. — When injured, lammerlat oozes a milky sap-like resin. Here a honeybee is collecting the resins.

Defensive resin response of Lammerlat seed pods to Tephritid flies

When its seed pods are punctured, lammerlat immediately exudes a resin to seal the pod and protect the seeds within. The puncture is usually a sign that eggs have been laid by the tephritid fly. Seed pods were collected and examined. The larvae pupate in the pod after completing feeding. At Wolwekraal Nature Reserve (113ha) on the outskirts of Prince Albert are several populations of lammerlat where honeybees were immediately observed on the lammerlat collecting resin, but there were also milkweed bugs Spilostethos, muscid flies, and allodapine bees at various locations on the plant. The allodapines collected mostly nectar from the flowers together with a male Coelioxys kleptoparasite bee.

An Allodapine bee foraging on the lammerlat flower. — A male Coelioxys kleptoparasite bee.

Then a fly which initially looked very wasp-like was spotted on the seed pods. Sue Milton-Dean who offers guided walks on a trail through the nature reserve had studied tephritid flies in Pteronia seeds. One of the conclusions of this study was that flowering and number of seeds containing tephritid fly embryos, were positively correlated with annual rainfall. Sue had a keen eye for these flies. This tephritid fly which was later identified as most probably Dacus bistrigulatus, was laying an egg into the seed pods. We collected a number of seed pods with visible resin and later dissected them under a microscope. Inside each seed pod a larva was found which Sue recognised as a tephritid larva. In seed pods where all of the seeds had been eaten, the biggest mature larvae were found prior to pupation.

A tephritid fly laying an egg into the seed pod.

Tephritid fly larva consumes the seeds as it develops. — The fly larva consumes the seeds as it develops.

Role of resins in honeybee nest construction

The bees collecting the exudate possibly originated from the two wild honeybee nests located in aardvark burrows on the reserve. At these nests honeybees were seen preparing the surface of the burrow for the application of propolis, enabling the colony to either increase the number and/or length of combs, thereby expanding the size of the colony. Once the surface had been cleaned by worker bees, resins were brought in by the resin-collecting foragers to be used as a sealant. Many of the resins used within a honeybee nest are the main components in propolis. These resins often have beeswax added to it to be more pliable, but can also consist of pure plant exudates in outer structures where it adheres tightly to the substrate, even if the substrate is partly loose.

The resins of Vachellia karroo being collected by a resin-collecting honeybee.

Once the propolis is adhered to the substrate, comb building begins and the colony is able to expand to the outer edges of the adhered propolis. Elsewhere in the nest architecture, propolis may incorporate sand grains or plant material to strengthen it. Its thickness depends on where the propolis is being applied and its purpose. Resins play an important and essential role in honeybee nests, far beyond being a sealant. Being defensive chemical exudates of plants, propolis has many anti-bacterial and anti-fungal properties and is aromatic and health-giving with its essential oils. Lammerlat resin as propolis with its cardiac-glycosidic properties could perhaps be beneficial for honeybees in ways that are not yet known, possibly also as a defence mechanism against predators of honeybees, or ants, wax moth larvae and the like. An interesting aspect to consider would be whether the use of propolis for human consumption containing lammerlat resins could be toxic if taken in high doses.

Honeybees preparing the surface and applying resins in a cavity dwelling situated in an aardvark burrow.

In a second cavity situated in an aardvark burrow honeybees prepare surface soils and apply propolis with lammerlat resins. — Honeybees preparing the surface and applying resins in a cavity dwelling situated in an aardvark burrow.

Ecosystem dynamics of Lammerlat

Recently on one of Sue’s nature walks at Wolwekraal, both Rufous-eared warblers and the Karoo eremomelas were seen eating tephritid larvae on the lammerlat. It has also been found that the larvae of these flies are themselves parasitised by a small wasp. The ecological cycle around this arid shrubland species is both complex and remarkable.

A Rufous-eared warbler ((Malcorus pectoralis) photographed here on a Vachellia karroo tree.

SELECTED REFERENCES:

Bruyns, P.V. (2002). The Stapeliads of Southern Africa and Madagascar Volume 1 pg 57.Umdaus Press, 329 pgs
Ellis J.D. Jr and Hepburn, H.R. (2003). A note on mapping propolis deposits in Cape honeybee (Apis mellifera capensis) colonies. African Entomology 11(1): 122-124.
Ghisalberti, E.L. (1979) Propolis: A review. Bee World 60(2):59-84.
Iannuzzi, J. (1983). Propolis: The most mysterious hive element. American Bee Journal 123(8): 573-575.
Iannuzzi, J. (1983). Propolis: The most mysterious hive element Part II – Conclusion. American Bee Journal 123(9): 631-633.
Milton, S.J. (1995), Effects of rain, sheep and tephritid flies on seed production of two arid Karoo shrubs in South Africa, Journal of Applied Ecology 32, 137-144.
Tribe G.D., Tautz J, Sternberg K and Cullinan, J. (2017). Firewalls in bee nests – survival value of propolis walls of wild Cape honeybee (Apis mellifera capensis). Sci. Nat. 104:29. DOI 10.1007/s00114-017-1449-5
Whiteman, N. (2023), Most Delicious Poison, Little, Brown Spark.