What Is the Point of Wasps? Why Wasps Matter in Nature

Wasps are much more than yellowjackets

When people ask what wasps are for, they usually mean the yellow-and-black social wasps that visit picnics, such as the common wasp. These are only a tiny fraction of the group. Scientists have described well over 100,000 species of wasps, and many more are still unnamed. Some biologists think that wasps, mostly tiny parasitic species, may turn out to be the most species-rich group of animals on Earth.

Most wasps are solitary: each female builds her own nest or lays her eggs without help, and many never sting people at all. They range from fairyflies, parasitic wasps that include the smallest known insects at less than 0.2 mm long, to tarantula hawks that hunt spiders many times their own weight. Bees and ants evolved from wasp ancestors, and bees are essentially wasps that switched from meat to pollen; see bee vs wasp.

Natural pest controllers

Social wasps feed their larvae almost entirely on animal food. Through the summer, the workers of a single colony make thousands of hunting trips, bringing back caterpillars, flies, spiders and other small animals chewed into balls of meat. Many of these prey are insects that eat crops and garden plants, such as the caterpillars of cabbage white butterflies and other moths.

This hunting has real value to farmers and gardeners, even though it is hard to measure. Social wasps are generalists, taking whatever prey is common, so they tend to hit the insects that are most abundant, including outbreaks of crop pests. Paper wasps play a similar role in North American gardens and fields.

Parasitoid wasps: hidden controllers

The biggest impact of wasps comes from species most people never notice. Parasitoid wasps lay their eggs on or inside other insects or spiders, and the wasp larvae feed on the host, eventually killing it. There may be around 100,000 species in just two families, the ichneumon wasps and braconid wasps, and almost every major group of insects has parasitoid wasps that attack it.

Many parasitoids are highly specialized, attacking only one host species or a small group. They attack eggs, caterpillars, aphids, beetle larvae and flies, and they are a major reason why plant-eating insects rarely strip whole forests and fields. Growers make deliberate use of them: the tiny wasp Encarsia formosa, for example, has been used against whiteflies on greenhouse tomatoes and cucumbers since the 1920s.

Wasps as pollinators

Adult wasps need sugar for energy, and they get much of it from flowers. They visit many open, easy-to-reach flowers, such as ivy, umbellifers like wild parsnip and fennel, and fruit trees, and they carry pollen from flower to flower, though less efficiently than hairy bees. Some plants rely heavily on wasps, including figworts and the broad-leaved helleborine, a European orchid.

The most remarkable wasp pollinators are fig wasps. More than 750 species of fig trees are each pollinated by tiny fig wasps, usually by their own particular species. The female wasp crawls inside the closed fig, which is really a cluster of hidden flowers, pollinates it and lays her eggs there; her young grow up inside and the new females carry pollen to the next fig. Without fig wasps there would be no wild figs, and fig fruits are vital food for monkeys, bats, birds and many other animals in tropical forests.

Some orchids trick male wasps into pollinating them. The Australian hammer orchids and the European mirror orchid produce scents that mimic female wasps, and males that try to mate with the flower pick up and deliver pollen.

Food for birds, badgers and other animals

Wasps and their nests are an important food source. A large wasp nest holds thousands of protein-rich larvae and pupae, and several animals have learned to raid them despite the stings. The European honey buzzard, a bird of prey that spends the summer in Europe, feeds its chicks largely on wasp larvae it digs out of nests. European badgers dig up wasp nests too; see what do badgers eat? In North America, skunks, raccoons and bears dig out yellowjacket nests.

Adult wasps are eaten by European bee-eaters, which rub off the sting before swallowing, and by hornets, robber flies and spiders. Several hoverflies and beetles have larvae that live inside wasp nests, feeding on debris or on the wasp brood.

Scavengers, recyclers and inventors of paper

Social wasps are also scavengers. They pick at dead insects, carcasses and fallen fruit, helping to break down and recycle material that would otherwise rot more slowly.

Wasps even taught people something. Social wasps build their nests from paper they make by chewing wood fibers and mixing them with saliva. In 1719 the French scientist René-Antoine Ferchault de Réaumur, after watching wasps at work, suggested that paper could be made from wood instead of rags. It took more than a century for wood pulp paper to catch on, but today most of the world’s paper is made that way.

Living alongside wasps

None of this makes a wasp sting less painful, and wasps can be a real nuisance in late summer, when colonies are at their largest and workers search for sugar; why are wasps more aggressive in late summer? explains why. For most people, though, the risk is small. Wasps away from the nest sting mainly when trapped, swatted or squeezed, so calm movements and keeping clear of nests prevent most stings.

Anyone who has a severe reaction to a sting, such as trouble breathing, swelling of the face or throat, or feeling faint, should seek emergency medical help immediately: call 911 in the US, 112 in the EU or 999 in the UK.

Like bees, wasps are part of the web that keeps ecosystems working. They hunt, pollinate, recycle and feed others, and a summer without wasps would be a summer with far more caterpillars and flies.