There are two types of cicadas commonly found in large numbers in Illinois. There are dogday or annual cicadas that emerge every year. Periodical cicadas emerge every 13 years in the southern half of Illinois and every 17 years in the northern half of the state. Cicadas are large bodied and have large compound eyes.
Cicadas are sometimes mistakenly called locusts. In actuality, they are not at all related to locusts, which are a kind of grasshopper. The male cicadas “sing” during the day to attract females. Dogday cicadas tend to sing more in late afternoon and evening. Each cicada species has its own distinctive sound to avoid attracting the wrong cicada. Typically, periodical cicada emergences consist of three species, that can be distinguished by the male songs as well as by slight differences in their appearance. The nymphs of these cicadas feed on the roots of trees and shrubs.
There are many species of dogday cicadas (also called harvestflies.) They are about 1¼ to 1½ inches long and from ½ to 7/16 inch wide. Some species may be as long as two inches. The wings are clear membranes except for the green coloring along the leading edge of each wing. The wings are one and a half inches to two inches long depending on body size. The upper body has a green and brown pattern to green and black pattern while the lower half of the body is mostly whitish.
Periodical cicadas are also edible. Native Americans utilized them in their diet. In 1990, several college students were filmed eating them alive. When asked what they tasted like, the students reported that they tasted like almonds. Drying them in a microwave oven carefully causes them to release an almond smell.