What Good Are Wasps?

How Some Wasps Do More Good Than Harm

Wasp nest
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What good could a wasp possibly be? When most people think about wasps, they think about being stung. Indeed, wasps do sting, and wasp stings hurt. To make matters worse, some wasps can be downright nuisances. They build nests under our eaves or in our lawns and swarm around our guests at backyard barbecues. If your experiences with wasps are all negative, you're probably wondering why we need these pests at all. What do wasps do, and why do we need them?

Thousands of Wasp Species

The term "wasp" is used to describe thousands of species within the order Hymenoptera. These groups include the parasitic wasps, like ichneumonids and braconids; hunting wasps, like mud daubers, digger wasps, and spider wasps; and pollinators like fig wasps.

Paper wasps, hornets, and yellowjackets all belong to the same family, the Vespidae. These social wasps share the ability to construct their nests of wood fibers, which are carefully chewed into pulp by the wasps and molded into paper.

That may not sound like good news to those of you who have been aggravated by the yellowjackets hanging around your garbage cans, or terrified by the huge hornets' nest you just discovered in the shrub near your pool. We take notice of the social wasps because they build visible nests, often close to our own homes and because they will defend these nests aggressively.


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Benefits of Wasps

As a group, wasps provide extraordinarily important ecological services, including pollination, predation, and parasitism. Put simply, without wasps we would be overrun with insect pests, and we would have no figs, and no Fig Newtons.

Hornets and paper wasps prey on other insects and help keep pest insect populations under control. Paper wasps carry caterpillars and leaf beetle larvae back to their nests to feed their growing young. Hornets provision their nests with all manner of live insects to sate the appetites of their developing larvae. It takes a lot of bugs to feed a hungry brood. Both hornets and paper wasps provide vital pest control services.

Yellowjackets don't get quite as much credit for being beneficial, although they should. Yellowjackets mostly scavenge dead insects to feed their offspring. We do need these services, too, of course. What would the world be like if all the dead bugs just piled up? Unfortunately, their scavenging habits and their love of sugar puts them in close proximity to people, which almost never ends well for the yellowjacket or the person.

Wasps and Yeast

Researchers at the University of Florence recently discovered another important role of both hornets and paper wasps–they carry yeast cells in their guts. Yeast is an essential ingredient in making bread, beer, and wine, but we know very little about how yeast lives in the wild. The researchers found that wasps and hornets feed on late-season grapes, which are rich in wild yeast. The yeast survives the winter in the stomachs of hibernating queen wasps and is passed on to their offspring when the mother wasps regurgitate food for their young. The new generation of wasps carries the yeast back to the next season's grapes. So raise your glass to the wasps and hornets!

New Zealand Eradication Program

In some cases, however, the costs of wasps, particularly invasive species, far outweigh the benefits. In 2015, the Department of Conservation and Ministry for Primary Industries in New Zealand looked into the economic costs of the invasive species of German wasps (Vespula germanica) and common wasps (V. vulgaris) across industries, society, and the natural environment. They found that wasps cost New Zealand NZ$75 million each year, and projected a total cost of NZ$772 million between 2015 and 2050, 80 percent of which is associated with wasp predation on honeybees and the impacts on decreased pollination. Wasps kill bees and their larvae for protein, rob hives of honey, and consume 50 percent of the available honeydew, a food source for bees.

Over the past hundred years, New Zealand has taken on an extensive program of re-establishing biodiversity on several uninhabited islands, by removing feral goats, goats, pigs, and rats. Rats have been removed from more than 100 islands as of 2018. In 2015, Department of Conservation ran a pilot program on five public conservation land sites, testing a government-backed wasp bait called Vespex, and found a reduction of more than 95 percent of wasp activity. In early 2018, the New Zealand government began distributing information on how to set up wasp bait traps.


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