Nature Articles - Cicada Invasion!                                 

Cicada Invasion!
By Al Winstel, Sharon Woods Naturalist Retired

What are these creatures that thrust themselves into our presence without regard for anything else going on in our lives? Worldwide, there are at least 1,000 species of these members of the order Hemiptera, a group of sucking insects. Relatives include leafhoppers and several groups – whitefly, aphids and scale insects - that are feared by the gardeners among us. Cicadas are a bright spot in this rogues’ gallery, seldom being implicated in domestic plant damage.

Locally, we have three species of 17-year cicadas, which may be differentiated by their calls, size and coloring, although you are unlikely to notice the difference unless looking for them. All three species tend to be pretty noisy.

They are generally small with orange eyes and orange wing veins. When they first emerge, their bodies appear white until they dry out. Then, the bodies are mostly black. One of the three species is larger, the other two being told apart by slight differences in the color of the abdomen. The 17-year cicadas emerge in May and June, followed by the annual cicadas, a larger insect with green wing veins. The annual species (of which there are several types locally) appears every year, although this is probably the result of overlapping generations rather than a one-year life cycle. The 17-year varieties have been around all along as white, six-legged soft-bodied animals living in the soil and feeding on root juices.

It’s theorized that the huge emergence of 17-year cicadas is a way to swamp predators with food or perhaps make it difficult for parasites to complete a life cycle in the cicadas. Many are eaten before breeding, but predators (some snakes, birds, foxes and maybe even your dog or cat) pass by many individuals after they have filled their stomachs. The cicadas are noisy and do not really have any good ways to defend themselves, so the predator swamping is their escape strategy. It’s also possible that the call volume has a repellant effect on predators at close range and that the mixture of several species’ calls may be more repellent than one species’ output. Although a particular brood tends to appear at 17-year intervals, there are 12 named broods, which sometimes occur in common geographic areas (we have four, possibly five broods in Ohio). As a result, it may be possible to have one brood emerge in eastern Hamilton County and another emerge in western Hamilton County at a much shorter interval than 17 years. That is why we have an emergence on the eastern edge of the county this year. How the annual or dog day cicada species manages to survive without producing huge numbers in a short time is a riddle, but apparently they are successful enough to still be around.

Acknowledgement: Much of the information above comes from the work of the late Dr. Monte Lloyd of the University of Chicago and from In Ohio’s Backyard: Periodical Cicadas by Dr. Gene Kritsky of Mt. St. Joseph College. Cicada fans might also visit the website www.cicadamania.com and watch for local updates at www.msj.edu/cicada.