Cicada season in Illinois: How long do they live? Are they harmful? All you need to know

Cicadas are back in the Chicago area and across Illinois, with the fascinating insects popping out of the soil. Trillions of periodical cicadas have been emerging this year, marking the first time in 17 years that this has happened. While the spectacle is captivating and interesting for some, it is rather unsettling for others.

Illinois witnesses both annual and periodical cicadas, with the annual ones appearing every year, and the periodical ones emerging every 13 or 17 years in large numbers. The periodical cicadas are in the spotlight this year. They have lived underground for 17 long years and fed on tree roots until they finally emerged.

Why are there so many cicadas in Illinois?

The Insect Asylum says that a rise in humidity levels can play a role in cicadas emerging in Illinois. As humidity levels rise, it is likely that sightings will climb. The insects generally begin emerging above the ground when the soil warms. This happens around late May or early June.

How long do cicadas live?

National Geographic says that the lifespan of cicadas varies, as there are more than 3,000 species. After the male and female cicadas have mated, and eggs have been laid, the eggs hatch about six weeks later.

The babies fall to the ground and dig themselves into the soil, where they live for 13 or 17 years. However, the parents die shortly after the mating process. They last above the ground for only about a month.

Are cicadas bad to have in your yard and are they harmful?

Cicadas are not essentially harmful, so having them in our yard is not a big problem. They feed only on plants and trees, do not bite or sting people, and do not spread any disease. However, cicadas are very loud, which can lead to disturbance in some cases.

Why are cicadas so loud?

Cicadas make their loud sounds with a corrugated exoskeletal structure in the thorax called a tymbal, according to Daily Science. The tymbal is an organ meant to produce sound.

According to Derke Hughes of the Naval Undersea Warfare Center, if a human body were like a cicada’s body, it "would have a thick set of muscles on either side of your torso that would allow you to cave in your chest so far that all your ribs would buckle inward one at a time into a deformed position. Releasing the muscle would allow your ribs to snap back to their regular shape, and then pulling the muscle again would repeat this."

Extension entomologist P.J. Liesch of the University of Wisconsin-Madison told CBS 58 in Milwaukee that several singing cicadas in a grove of trees could reach 70 to 80 decibels – almost as loud as a vacuum cleaner.