Wasps belong to the order Hymenoptera, covering tens of thousands of species with varied lifestyles and diets. A significant part of their life cycle involves consuming other insects or arthropods. This consumption is driven by a biological need tied to the development of their young. The insects they consume range from common garden pests to specialized prey, which are either actively hunted or passively hosted.
Adult Energy Sources Versus Larval Protein
The primary reason wasps hunt insects is not for their own nutrition, but for the growth and development of their larvae. Adult wasps, whether social like yellowjackets or solitary, require quick energy to fuel their high-activity lives of flying and foraging. They fulfill this need by consuming high-sugar liquids, such as nectar from flowers, tree sap, and honeydew secreted by aphids.
The developing larvae require a diet rich in protein to rapidly grow and metamorphose. Adult worker wasps actively hunt and process other insects, which they then feed to their young. In social species, the larvae secrete a sugary fluid that the adults consume, creating a reciprocal system where the larvae provide sugar in exchange for protein. This division in diet—sugar for adults and protein for larvae—drives their predatory behavior.
The Hunters: Prey of Social and Solitary Wasps
Actively predatory wasps, including both social species and many solitary ones, physically subdue and dismember their prey before returning it to a nest chamber. Social wasps, such as yellowjackets and paper wasps, are generalist hunters that target a wide variety of soft-bodied insects. Their most common prey includes flies, caterpillars, and aphids, which they chew into a manageable paste for their larvae.
Solitary wasps often exhibit specialized hunting behaviors, provisioning their nests with specific types of prey. Mud daubers and potter wasps frequently stock their nests with paralyzed spiders, while cicada killer wasps exclusively target cicadas. These species use their stingers to immobilize the prey, which remains alive but paralyzed, ensuring a fresh protein source for their emerging young.
The Hosts: Insects Targeted by Parasitic Wasps
The vast majority of wasps belong to the group known as parasitoids, including families like the Ichneumonidae and Braconidae. They do not hunt to feed themselves or their larvae directly, but instead lay their eggs in or on a host insect. The host—which can be an egg, larva, pupa, or adult—is then consumed internally by the developing wasp larva.
These parasitoid wasps are highly specialized, with different species targeting specific host insects. Common hosts are agricultural pests:
- Aphids
- Beetle grubs
- Whiteflies
- Larvae of moths and butterflies (caterpillars)
For example, Trichogramma wasps lay their eggs inside the eggs of over 200 species of moths and butterflies, while other species attack scale insects and mealybugs.
Wasp Diet and Natural Pest Control
Because of their predatory and parasitic habits, wasps provide a major ecological service for humans. Wasps act as biological control agents by naturally suppressing populations of insect pests that damage crops and gardens. Social wasps like yellowjackets and paper wasps actively hunt caterpillars, flies, and aphids, significantly reducing the pressure these pests place on plants.
Parasitoid wasps are particularly valuable in managed ecosystems because they are highly efficient at seeking out and eliminating specific target pests. The commercial use of species like Encarsia formosa to control whiteflies in greenhouses and the release of parasitic wasps to reduce emerald ash borer populations demonstrate their economic benefit. This natural predation helps regulate insect numbers and reduces the need for chemical pesticides.