Wasps, members of the insect order Hymenoptera, are highly beneficial insects that help regulate populations of agricultural and garden pests, consuming millions of insects each season. Their reputation as bothersome insects often overshadows this ecological role. Understanding what wasps eat requires recognizing that their diet changes dramatically based on their life stage and the needs of their colony. This shifting diet is the primary factor driving their foraging behavior.
The Fundamental Diet Split: Energy for Adults, Protein for Larvae
The most significant aspect of a social wasp’s diet is the division of labor between the adults and the developing young. Adult worker wasps require a constant supply of simple carbohydrates for flight and colony maintenance. Their narrow abdominal constriction, the “wasp waist,” limits the passage of solid food, meaning they cannot effectively digest the protein they hunt.
Wasp larvae, conversely, require large amounts of protein to fuel their rapid growth and metamorphosis into adult wasps. The adult workers hunt and chew up protein-rich prey into a digestible paste, which they then feed directly to the larvae in the nest. The larvae secrete a sugar-rich liquid that the adult workers consume as their primary source of carbohydrates.
This exchange ensures the colony’s survival during the peak summer months, as the young supply the adults with energy in return for protein. Once the colony begins to wind down in late summer, the production of these sugary secretions slows as the larvae mature, forcing adult workers to seek external sugar sources.
Wasp Foraging: From Natural Prey to Sweet Scavenging
Adult wasps obtain their high-energy carbohydrate requirements from various natural sources. Common food sources include the nectar from flowers, which also makes them incidental pollinators, though less efficient than bees. They also seek out tree sap, especially from damaged trees, and honeydew, a sugary excretion produced by aphids and other plant-sucking insects.
These natural sugar sources provide the fuel for workers to perform their main task: hunting protein for the larvae. Social wasps are effective predators that target a wide range of soft-bodied invertebrates. They commonly take flies, spiders, and especially caterpillars, which are a major source of protein for the growing brood.
A single mature wasp colony can consume millions of insects over a summer. The workers will also scavenge for protein from carrion or dead insects they find in the environment to supplement their live prey hunting. This intensive foraging for protein is most pronounced in the spring and early summer when the colony is expanding quickly and the demand from the larvae is highest.
Understanding Nuisance Behavior
The common perception of wasps as a nuisance often peaks in late summer and early autumn when their dietary focus shifts dramatically. As the queen stops laying eggs and the final generation of larvae matures, the adult workers lose their internal source of sugary liquid from the young. This loss of their primary energy source drives them to search aggressively for external carbohydrates.
This search frequently brings them into conflict with humans at picnics, outdoor dining areas, and garbage receptacles. They are strongly attracted to exposed human food sources, including sugary drinks, ice cream, ripe or fermented fruit, and meat scraps. Their scavenging behavior is also directed toward pet food left outdoors and the contents of uncovered garbage cans.
This change in behavior is compounded because the colony population is at its highest point, meaning many workers are competing for fewer natural resources. When they are drawn to human settings, the combination of their heightened need for sugar and the increased number of foraging individuals often leads to the encounters that make them seem more aggressive during this time of year.