Have cicadas arrived a few years early?

Dear Tom,
The cicada noise in the evenings here is deafening. Aren’t they a few years early?
— Brigit Welch, Tinley Park

Dear Brigit,
The cicadas you are hearing are not the 17-year cicadas, which are not due until 2024, but “annual” cicadas that have multiple-year life cycles that are not precisely synchronized, and adults emerge every year. The infamous 17-year cicadas, common in Illinois and the Midwest, last emerged in 2007 and prior to that in 1956, 1973 and 1990. These cicadas’ life cycles are genetically driven and not affected by weather, other than the fact that the nymphs will emerge from the ground in spring when the soil temperatures reach about 64 degrees. The cicadas are about 4 centimeters long, and while deafening and overwhelming in number, they do not sting or bite.