Tree Body of Palos Park
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Periodical Cicadas

After a long, at times quiet, but often disruptive 17 year dirt nap, billions of “Periodical Cicadas” have begun their infrequent migration out of the earth to restart their lengthy reproduction process. This only occurs 6 times every century. Adult cicadas are not harmful to humans or animals. They are more of an annoyance than anything. 


“Periodical Cicadas” surface every 17 years when the soil surface hits an average temperature of 65 degrees typically beginning in late May. These cicadas have a shiny, jet black body, are green to black in color with transparent silvery wings, and are about 1.5 inches long. 

The female cicadas lay their eggs, sometimes up to 600 eggs per cicada, along twigs and branches of a tree. Established trees rarely suffer any severe damage from the cicadas, however some limbs and branches may occasionally die off from the egg laying process. Some smaller trees or seedlings may suffer severe damage and possibly die.     

The eggs will hatch in six to seven weeks. The nymphs fall to the ground and burrow into the soil, seeking suitable roots to attach to. The cicada nymphs suck sap from roots until the last year of their life 17-year cycle. After completing the seventeen-year cycle, the full-grown nymphs make their way up to the surface where they crawl up the closest tree trunk. The outer covering of the nymph splits open, and the winged adult emerges.  The adult cicada will live for 20-25 days, not to be seen again for 17 years or until 2034. 

The University of Illinois states that an average of 133,000 cicadas will surface per acre, with the possibility of an emergence rate of 1.5 million per acre, depending on the location.