Large amounts of rain have delayed the cicada killers but they are back. We are receiving numerous phone calls about these wasp-like insects asking what these bugs are about. The cicada killers are large and can get up to 2.5 inches long. These insects are complementary to the wasp however they are not social in habit. The cicada killers are identified under the category Solitary Wasps signifying that they do not create colonies with numbers of workers, they rarely sting in defense of their nest and there is no medical risk if stung.
The female cicada killers burrow under the ground into a dry area where there is light textured soil with full sunlight. After digging the tunnel, the female wasp locates a cicada in a tree or bush and then inflicts a very precise, paralyzing sting before dragging it to the entrance of its burrow. After stuffing the cicada into a small nursery cell, the wasp lays an egg, and then seals off the chamber. The egg hatches in 2-3 days, then the larva burrow into the cicada carcass and begin devouring the still-living cicada. They overwinter in their cells, emerging the next July as adults. Between mating and mid-August, new adults dig soil burrows, stock them with cicadas, and the cycle is repeated. Adults die by mid-September.
A large nesting aggregation sometimes results in unsightly mounds of soil that are the remains of the tunnel excavation. Otherwise, cicada killers do very little damage.
A safe and efficient way to control these insects is done by placing a small amount of 5% carbaryl (Sevin) dust down into the soil tunnel entrance. In the case where there is a large nest the area can be sprayed. With both of these situations, the tunnel entrances should stay left open so the wasps are provoked into the treated area.
Please contact your local Purdue Extension Office if you have questions or concerns:
In Porter County, the Agriculture & Natural Resources Educator is Lyndsay Ploehn and she can be reached at 219-465-3555.
Resources: Purdue Extension Publication E-254-W by Timothy Gibb, Extension Entomologist
Purdue Plant & Pest Diagnostics Lab
Photos: Purdue Plant & Pest Diagnostics Lab & Michigan State University Extension
Species Information: Sphecius speciosus (Drury) – Cicada killer