WASP. A word that strikes fear into the heart of many a summer picnic. These widely scorned insects, mostly viewed with annoyance and fear, simply can’t get enough of our lunches. They loiter around bins and jam jars, with a threatening drone. Sometimes they land on us. Sometimes they sting. So unloved are they, that we tend to describe people with selfish, malicious or bad-tempered dispositions as “waspish.” Some detractors might go so far as to ask the question: what use is a wasp, anyway?
Well, you might be surprised. Consider for a moment that your knowledge of wasps might not stretch any further than the common wasp Vespula vulgaris. Or, if you live in the USA, one of several species of yellowjackets. These social wasps live in colonies that contain thousands of workers, each tending to the queen’s offspring. The workers hunt insects to feed to the wasp brood, and in return, the tiny grubs reward the workers by secreting a sugary substance. However, at the end of the summer, when the queen dies and all the larvae have pupated into adult wasps, the workers have to look elsewhere for their sugar fix. And that leads them straight to your picnic table.
But these species are just a miniscule fraction of an enormously diverse array of wasps that includes over 100,000 known species. Yes, some of them deal out stings, but 70,000 of them don’t. In fact, not only are the majority of wasps harmless to humans, science has shown that we actually depend on them. Wasps are valuable to ecosystems, to our economy, even to human health. Their venom and saliva have antibiotic properties, and there is promising evidence that the venom of some wasp species could even be used to fight cancer.
Wasps as Pollinators
Pollination by insects is vital for agriculture, and its economic importance has been valued at greater than $250 billion (US) per year worldwide. Bees, which also sting, are prized for pollinating our crops, but wasps—also superb pollinators—are rarely afforded the same credit. Ever enjoyed a fig? Well, you have wasps to thank! There are other plants too, including several beautiful orchid species, that are completely dependent on wasps for pollination.
Wasps and figs Fig wasps (Agaonidae) rely on fig trees to provide a nursery for their young, and the fig plants rely on the wasp to pollinate their flowers (a relationship known as obligate mutualism). A female wasp has to crawl through a small opening into a fig fruit to access these flowers, which are hidden within it. Once inside, she lays her eggs and the young hatch, mate and then travel on to other figs, spreading the pollen from the flower they grew up in. Without the fig wasps, there would be no fig fruit for people or animals to enjoy.
Wasps and orchids
Orchids use the allure of sex and drugs to attract their wasp pollinators. The King Spider Orchid (Caladenia pectinata) manufactures chemicals that mimic the sex pheromones of a receptive female wasp, while the wasp orchid ( practices a more visual deception, imitating the colouration of a female wasp. In both cases, amorous male wasps are drawn to the orchids, where they attempt to mate with the flowers and pick up pollen in the process.
The broad-leaved helleborine (Epipactis helloborine) goes even further, using mind-altering substances to keep wasps and other pollinating insects coming back to it. Some research suggests its nectar contains fermented alcohol, or is laced with opiates. Either way, as the wasp reaches for the intoxicating libation, the flower deposits its entire male sexual organ (the pollinium) on the insect’s head, which the stupefied visitor is powerless to remove.
Wasps as pest controllers
Alongside scavenging picnics, wasps also hunt invertebrates, including aphids and caterpillars that damage crops and garden plants. This makes wasps a natural form of pest control and allies them with farmers and gardeners alike. Biocontrol (where insects or pathogens are used to protect crops from pests) is worth at least $416 billion (US) per year worldwide. But wasps regulate crop-eating pests for free, managing pests on high-value crops such as maize and sugarcane. As apex predators, wasps also help to keep their native ecosystems in balance. Without them, the world could be overrun with spiders and other insects.
Spider Hunters
Armed with one of the most painful stings on the planet, tarantula hawks are a spider’s worst nightmare. Even though the tarantula is considerably larger than the wasp, the stinging insect packs a venom that permanently paralyses (but doesn’t kill) the tarantula. The female lays a single egg on the victim’s body – which then provides a source of fresh food for the larva.
The Golden Spider Wasp of Australia uses a similar strategy of paralysing its prey, which is dragged to the wasp’s burrow and eaten alive by the larva, which consume the least important parts of the spider first, to keep it fresh (and alive) for longer. The skin of the spider is eventually used for the wasp’s cocoon. Photographer Jiri Lochman says: “The Female Spider Hunter Wasp is a courageous beast. After all, the spiders it preys on are equipped with potent venom too, and it is never a foregone conclusion that the wasp will end up victorious. But these wasps are skilled hunters and spiders seem to be mesmerized by their antics as they dance around their victims, flickering their colourful antennae.”
Bee Hunters
One wasp species has earned itself the name ‘Beewolf’ (Philanthus triangulum). These wasps specifically prey upon worker honeybees (Apis mellifera). The female wasp will catch up to six bees at a time, take them to her nest chamber and lay a single egg amongst them. The grub, when it hatches, then has a banquet to feast on before it emerges as an adult. Preying on honeybees might not seem like a positive impact, but even bee numbers must be kept in check. Honeybees can compete with other species of wild bees, potentially contributing to the decline in their numbers, especially where beehives are numerous. As a result, the Beewolf may be allowing space for these other species to feed.
Caterpillar hunters
Other wasp species target caterpillars. These wasps in particular could be considered the gardener’s or farmer’s best friend, controlling species that may otherwise completely overrun a crop or ornamental garden. Usually, the caterpillars are paralyzed and carried back to the wasp’s burrow, to be consumed alive. Others prefer to eat on the go, like the larvae of the genus Glyptapanteles, which feed on a caterpillar whilst it is still moving and eating. Some caterpillar-hunting wasps are parasitic, laying their eggs inside a living caterpillar. When the eggs hatch, the larvae feed on the caterpillar’s insides and then burst out through its skin, before forming cocoons and maturing into adult wasps.
Wasps as food
Wasps are also a valuable food source, for other animals and even people. Larvae are harvested in some tropical countries for food, and in Japan, the giant hornet has long been considered a delicacy, pan-fried or steamed with rice.
Birds known as bee-eaters feed on wasps, which they de-sting by rubbing them against branches. These wasps are then sometimes presented as presents during their courtships, where one bird feeds another to strengthen their pair bonds.
Dragonflies and spiders also belong in the wasp-eating club, and the Mottled bee-fly is a known parasite of digger wasp nests. The fly flicks its eggs towards the entrance of the wasps’ burrows. Once they hatch, the young flies will crawl inside the nest, to eat the unsuspecting wasp larvae.
Wasps therefore help to sustain other species in the ecosystem. These species in turn bring their own benefits to their surrounding environment, ensuring that the wasps’ indirect positive influence is spread further.
Wasps as architects
Wasps are nature’s artists, creating intricate structures in which to live and breed. A wasps’ nest is an architectural marvel. Perhaps the most easily recognised are the nests built by paper wasps, which include the yellow-striped common wasps we are so familiar with, as well as hornets. These insects harvest cellulose from wood and plant stems, chewing it up with their saliva to form paper, in a very similar way to how we make it. They deposit this paper using their mandibles to carefully sculpt hexagonal brood chambers, much like a bee’s honeycomb. Hexagons are the most efficient shape, allowing the wasps maximum strength with minimal building material.
Wasps construct nests out of other materials, too. The female mud dauber wasp collects mud from the edges of water sources, working it into a ball with her forelegs and mandibles. She then mixes it with saliva, and moulds it into a multi-tiered nest of many cells. one for each of her larvae. Likewise, potter wasps get their name from the pot-shaped nests they fashion from mud and clay. In both cases, the female stocks her mud nest with live, paralysed prey, lays a single egg on in and then seals the nest to protect the developing larvae.
Digger Wasps
Some wasps do not bother with intricate designs, and are content with a hole in the ground. Digger wasps are usually associated with dry, sandy soils that are easy to burrow into. They will excavate tunnels that terminate in brood chambers. As usual, these chambers are provisioned with prey upon which the female lays her eggs before sealing up the hole. After pupating, the young wasps will then dig themselves out of the burrow and go on to continue the cycle.
Gall wasps
Gall wasps (Cynipidae) are a group of species that create growths on plants, in which their larvae develop. They do this by laying their eggs in leaves, flowers or buds. The eggs release chemicals that are toxic to the plant, forcing it to create a fleshy growth around the larvae to protect itself. This creates the perfect home for the gall wasp grub to grow up in. Once the larvae have developed into wasps, they dig themselves out of the gall and go on to parasitise more plants.
Weird & Wonderful Wasps
Wasps come in all shapes, sizes and colours. From the gigantic to the minute, to the exquisitely beautiful, wasps never cease to amaze.
Little and large
Wasps in the fairy fly family (Mymaridae) are tiny. They are so small that it affects how they experience physics. Air appears to be more like a liquid to them, thicker and harder to move through. In order to fly in such harsh conditions, fairy flies have developed stalked wings covered in tiny hairs to reduce drag. These are paddle shaped and they use them to ‘row’ through the air.
At the other end of the size spectrum is the Tarantula Hawk Wasp, a wasp so large that spiders of the tarantula family are it’s prey! They have a painful sting full of paralyzing venom, which they use to immobilize their enormous quarry. This sting is said to be one of the most painful in the world, second only to the bullet ant.
Nature’s jewels
Who knew wasps could be beautiful? With their glittering iridescence, members of the cuckoo wasp family deserve a place among the world’s most exquisite-looking insects. And check out the dazzling wings of this spider-hunting wasp!
Wingless Wasps
Not all wasps look like wasps, and this is especially true for the wingless species. The deceptively-named velvet ants (Mutillidae) are not ants at all – they’re parasitic wasps! But the wingless females are so superficially ant-like (narrow waist and all) that the confusion is warranted. Although velvet ants are restricted to life on the ground, they have swapped flight muscles for stronger legs, making them quick on their feet!
Likewise, female flower wasps (Thynnidae) have forsaken their wings for a flightless existence, but they can still hitch a ride with the winged males. When they are ready to mate, they climb to a high point and waft their abdomens to spread pheromones into the air. Once picked up by a male, the females will cling to her partner’s abdomen during “nuptial flights”. Wasp Photographer Jiri Lochman says: “In some species of flower wasp, both partners will feed on nectar as the male flies from flower to flower. In other species only the male feeds, passing nectar to the female mouth-to-mouth, or exuding it from his abdomen for her. These nuptial flights can take many hours.” Once back on the ground, the female flower wasp will dig for beetle grubs, which she paralyses to provide food for her offspring.
In the end…
None of these facts make the wasps we encounter any less bothersome. But these underappreciated insects deserve better. They help us, and (dare we say it) they are even quite wonderful. Given the chance, they could be just as beloved as bees.
So the next time you see a wasp, don’t be so quick to swat at it (that would probably make it more likely to sting you anyway). Remember the benefits it brings to your local ecosystem, to the food you eat, and perhaps, one day, to human medicine.
And if the wasp is after your sausages, lemonade, or jam? Why not offer it a small share and gradually move the plate further away from your picnic table. That way, both wasp and human can enjoy their lunch in peace.
Wasps of the World, from Princeton University Press, is scheduled for publication on 9th April, 2024. Nature Picture Library collaborated with Jane Smith Media to supply many images for the book, and our research inspired this blog post.
