For the last several weeks, the incessant pulsating drone of dog day cicadas reminds us that it's hot. It's also a reminder to be on the lookout for a monstrous but usually harmless wasp, the cicada killer.
By insect standards, the cicada killer is huge. Females grow to 2 inches long, and the bright yellow bands on the dark abdomen identify them immediately as a wasp. They live up to 75 days, and unlike yellow jackets and hornets, cicada killers are solitary. Because they are so big, cicada killers strike fear into the hearts of some people. But males lack stingers and females are generally docile toward people.
Cicada killers emerge in July shortly after dog day cicadas appear. The breeding biology of cicada killers justifies the common name. In August, females search for well-drained sandy soils in which to excavate nesting tunnels. Watch for them along sandy river beaches and at ball fields, sand volleyball courts and sand traps on golf courses.
After mating, females dig a tunnel about 6 inches deep in dry sandy soil, then turn the tunnel at a right angle for another 6 inches. At the end of the tunnel, a larger nesting chamber is formed.
Female killers then search trees for cicadas. Because female cicadas don't sing and are taken as often as males, which do sing, it is suspected that they are located by sight.
When a cicada is found, the female cicada killer stings it and injects its paralyzing venom. After the cicada is incapacitated, the killer grabs it lengthwise and glides down to its burrow. If the kill occurred on the ground, the killer drags the cicada to its burrow.
In the nest chamber at the end of the tunnel, the killer lays an egg on the still living, paralyzed cicada. She then seals the tunnel and repeats the process.
After just a few days the egg hatches, and the larval killer begins eating the paralyzed cicada. By the end of summer, the cicada is consumed and the larval killer spins a cocoon and spends the winter underground.
The following summer a new generation of cicada killers emerges.
Curiously, adult cicada killers subsist on nectar.
Scott Shalaway is a biologist and author. His other weekly Post-Gazette column, "Wildlife," runs Sundays on the outdoors page in Sports. He can be reached at firstname.lastname@example.org or RD 5, Cameron, WV 26033.