Beneficial Insect Files: Cicada Killer Wasp

During the hot summer months, usually towards the end of July and into the early part of August, we begin to see many large wasps in Central Texas. These wasps are pale yellow and black and resemble yellow jackets, only these are much bigger and scarier looking. In fact, they are the largest wasp species in Central Texas (growing over an inch long). Meet the Cicada Killer Wasp.

Unlike many of its cousins, the cicada killer is mostly non-aggressive and rarely stings.  Males may fly at you when you approach their burrows or nectar sources, but luckily, they are incapable of stinging.   Female cicada killers are reported to sting only if provoked, (i.e. handled or stepped on).  Instead of using their stingers to defend their nest and attack aggressors like most wasps, female cicada killers use their stingers only to do the function they are named for: killing cidadas.  Their sting, however, does not actually kill the cicada; it permanently paralyzes them (1).

Cicada killers go after those noisy, chattering (some call it singing, but I don’t!) adult cidadas that seem to swell in numbers towards the middle of the summer.  You can find their alien-looking shells (actually a molted exoskeleton) on the sides of trees in early to mid summer.   Once they molt, then they start making noise by vibrating their tymbal muscles, which produces loud clicks as two tymbal membranes pop in and pop out.  This sound, albeit a beautiful love song between courting cicadas, leads the cicada killer wasp right to them.  Once stung by the  cicada killer wasp, the cicada takes a permanent nap, while the female works on getting it back to its nest.

The cicada killer lives in burrows dug into soft dirt or sandy areas at ground level. In this burrow, a single wasp makes up to sixteen short tunnels or cells (2), just large enough to hold an adult cicada, all attached to the main passageway leading in and out of the burrow. The female wasp drags and carries her paralyzed victim any way she can all the way from the tops of the trees down to the ground and into the burrow. This is a strenuous activity as the adult cicada can be just as large as the wasp herself. Once in the burrow, the wasp tugs the cicada into one of the prepared cells, then deposits a single egg on to it. After this, the wasp seals the tunnel shut.

When the egg hatches and the wasp larvae emerges, it finds a quick and easy meal to hold it over until it is ready to emerge from the burrow as an adult. The lives of cicada killers are short as the adults do not overwinter. They live their life in a single season, capture cicadas and lay their young before expiring. The larvae emerge and overwinter in the prepared cicada tomb, feasting entirely on the cicada until they reach maturity and emerge the following spring.

Adult cicada killer wasps feed exclusively on flower nectar. As such, they are beneficial pollinators to a small degree, but are furthermore helpful in that they kill excessive cicada populations (3).

Did you know?

Cicada wasps are solitary, predatory wasps, though there may be several wasps living in close proximity to each other.

The female does all the work, from digging the burrow, to stinging and dragging the cicada back to the burrow, and from laying the eggs to sealing the cicada in. The sole purpose of the male is for mating.