The grand emergence of 17-year cicadas this year in the eastern United States is already causing quite a buzz.
Officially known as periodical cicadas, there are seven species of these large, tough and noisy insects in the United States. Three species have a 17-year cycle and four have a 13-year cycle.
There are 15 different “broods” of periodical cicadas in the country, with differing geographic ranges and cycling. The brood of adults that is emerging this year in many eastern seaboard states is Brood II. Brood X, in several Midwestern states, including southern Michigan, is not due for an emergence until 2021. Periodical cicadas are not found in northern Michigan, but we do have low numbers of “annual” cicadas (also called “dog-day” cicadas) that don’t have distinctly timed broods.
Adult cicadas feed on stems and branches of plants by sucking out sap. Even at high numbers, this is not particularly injurious to plants. However, there is great harm done to trees in the process of laying eggs. Females use their sharp ovipositor to insert eggs under the bark of branches, causing a die-back of the branch beyond the point of injury. This damage can be very widespread and destructive to trees in forests, landscapes and orchards.
A periodical cicada emergence typically raises quite a stir due to the awesome abundance of adults, but there is one more factor that really lets everyone know they are in town — noise! Male cicadas produce a unique, high-pitched, high-volume buzzing song to attract their mates. It can be so loud that it is difficult to carry on a conversation. I could hear cicadas in the background of phone calls from my brother in Maryland in 1996.
For more information on periodical cicadas and their relatives, try the following web sites:
(good technical information)
(good technical information and recordings of the songs of all the cicada species of Michigan)
(get involved in the hype!)