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Over the Garden Fence

The cicadas are coming (or already here)

If you have not already spotted them, be on the lookout for those bug-eyed insects with their persistent song in the canopies of your landscape. Yep, that’s right, cicadas are among us. In fact, some are even four years ahead of schedule. Learn more about that online in our Home, Yard, and Garden newsletter.

They show up not from above, but from below where they have been anywhere from one or two years to 17 years. Cicada feed on the sap from our shade trees that whole time. The ones that make themselves known every year are the ones we call “Dog Day” cicada. They are pretty good sized. You will see the shed carcasses attached to just about anything they can climb on to get some height. They will split the skin vertically along their back, pull themselves out to dry off while expanding their wings by pumping their “blood” into the veined membranes. Once the wings have expanded and dry, off they go to sing for a mate.

This past week other cicadas have been showing up. You may have seen these very round holes in the landscape beds and the lawn nearby. In 2020, we will get to see the 17-year cicada show up. This emergence is a sub-brood as they are known as Northern Illinois Sub-brood (part of Marlatt’s XIII). These cicadas are about half the size of the Dog Day version. They will be doing the same thing once above ground, singing and attracting a mate.

If you live in an older neighborhood with a lot of older mature trees, you can expect to find lots carcasses and hear a loud amount of singing. Newer subdivisions have not had enough trees long enough to support either the 13-year or 17-year cicada.

As an adult cicada, eating is not something they are interested in. While they will eat, any adult feeding damage is very minimal. Once mated the female will deposit eggs into smaller twigs and branches at the outer edges of the canopy.  Her ovipositor saws an incision lengthwise where a single or double row of eggs are laid. This is where homeowners are concerned about damage. Young and smaller trees with lots of those branches and twigs can be heavily damaged. It is not uncommon to see the ends of every branch flag and die by the end of the summer. The cicada eggs will take about 5 to 6 weeks to hatch, and at that point they fall to soil and burrow down to locate the tree roots where they will live for the next two to 17 years.

There really is not a practical way to prevent the egg-laying damage. On very young trees, homeowners have used bird netting if the holes are small enough to prevent Cicadas from getting through and completely covering the trees including tying the netting securely to the trunk. Damage can be both seen and found, including dieback, in the next growing season too.

Want to learn a bit more? Read how cicadas begin to emerge in 2020 from University of Illinois.

About the author: Richard Hentschel’s expertise extends across several subject areas with specialties in lawn care, fruit tree production, woody ornamentals, and home and community gardening. During his 45-year career in horticulture and agriculture, Hentschel became a well-known and respected expert for commercial and homeowner audiences, industry organizations, and media. He retired from University of Illinois Extension in April 2022 with nearly 30 years of service as a Horticulture Specialist and Educator in northern Illinois.