In May 2024, the 17 year cicada will appear in the northern part of Illinois while in the southern reaches, the 13 year cicada will emerge. It is unknown how periodical cicadas know when to emerge, but we know they emerge when soil temperatures are 64 degrees and spring rains have softened the soil, along with day temperatures in the low 80’s and night temperatures in the 70’s. This brood of cicadas has a reputation for the largest emergence of cicadas known anywhere. They are harmless to humans and do not bite or sting.
Cicada nymphs emerge from the soil creating tiny holes and crawl to any vertical object such as a tree, house, wood fence. Here they shed their exoskeleton that protected their wings and body while tunneling up. The skeleton remains and the adult cicada now pumps fluids into its wings and fly away. Periodical cicadas are black with red eyes and have transparent wings with red to orange veins. They are 1 ¼ to 1 ½ inches long. Their life cycle continues with brief feeding and mating (the noise or song they make). Females lay eggs, after 4 weeks both females and males die.
Cicadas can harm small deciduous trees and shrubs in their egg laying process and seldom damage evergreens. The female periodical cicada uses her ovipositor to make slits in small twigs of trees and shrubs up to 1 ½” long to lay hundreds of eggs. They hatch in 6 to 7 weeks and the nymphs fall to the ground, burrow into the soil, and attach to a root to feed for the next 13 or 17 years. These slits can cause the twigs to dry or break off. Damage to small trees and shrubs can be prevented by covering them with netting, cheesecloth, or tulle. One can also delay planting until July when the cicada’s life cycle is complete.
Both the Morton Arboretum and the Illinois Extension do not recommend insecticide use. Birds, racoons, dogs, cats, and other animals feast on cicadas. Cicadas do not like the smell of peppermint or getting wet. Newer housing developments may not see many due to the bulldozing of the soil removal of trees, and construction. Older neighborhoods that had seen thousands of cicadas in the past will have them again. On the plus side, cicadas at emergence do aerate the lawn and soils. They also add nutrition to the soil after they die and decompose, but the aroma of a thousand dead cicadas is a little repulsive.
The 13 and 17 year cicada are a true wonder of nature. Millions of insects will emerge for a fleeting time after 17 years of living underground.
