They are so named because they hunt cicadas and provision their nests with them. Cicada killers exert a measure of natural control on cicada populations, and as such they may directly benefit the deciduous trees upon which the cicadas feed.
Adult eastern cicada wasps are large, 0.6” to 2” long, robust wasps with hairy, reddish, and black areas on their thoraces (middle parts), and black to reddish brown abdominal (rear) segments that are marked with light yellow stripes. The wings are brownish. Coloration superficially resembles that of some yellowjacket and hornet species.
The females are somewhat larger than the males, and both are among the largest wasps seen in the Eastern United States, their unusual size giving them a uniquely fearsome appearance. The males are smaller than the females because they are not given as much larval food; since females must carry the cicadas they have killed to a burrow for nesting, they benefit from being larger, and are given more food as larvae.
Adults emerge in summer, typically beginning around late June or early July and die off in September or October. They are present in a given area for 60 to 75 days, usually until mid-September. The large females are commonly seen skimming around lawns seeking good sites to dig burrows and searching for cicadas in trees and taller shrubs.
The males are more often seen in groups, vigorously challenging one another for position on the breeding aggregation from which they emerged, and generally investigate anything that moves or flies near them. Not unusually, two or three male wasps are seen locked together in apparent midair combat, the aggregate adopting an erratic flight path until one of the wasps breaks away.
The male wasps’ aggressive behavior is similar to that of another robust insect of the area, the male carpenter bee. In both cases, while the males’ vigorous territorial defense can be frightening and intimidating to human passersby, the males pose no danger whatsoever. Male cicada killers only grapple with other insects and cannot sting.