I keep hearing about the cicadas that are coming out of the ground after 17-years. What are they and will we have them here?
Answered by Ron Patterson – University of Idaho Extension, Bonneville County
The famous chattering bugs. If you didn’t know better, you would think you are getting near a rattlesnake. We’re talking about cicadas.
Cicadas are large insects in the Order Hemiptera, Family Cicadidae. They are well-known for their vocal mating call. The boys are calling to the girls. There are at least 170 species of cicadas in North America, north of Mexico, which are tied to a geographical area and specific species plants for feed and laying eggs. Cicadas spend the majority of their life in the ground as nymphs (immature form of insects with incomplete metamorphosis). While cicadas do feed on trees, the damage is typically insignificant, even with their large numbers.
The most famous of the cicadas is the 17-year periodical cicada. The 17-year periodical cicada is found only in the eastern United States. There are several broods and each brood starts its 17-year cycle in a different year, and they often cover a different geographical area. The largest brood, Brood X, is slated to emerge in 2021. The Brood X range is from Tennessee to New York.
The chorus of 17-year cicadas begins to emerge when the ground warms up in early May, so they are already starting to sing their love song. During their brief four- to six-week life above-ground the adult cicadas mate, lay eggs, and then die. The eggs are laid on pencil-sized branches of trees. Once they hatch the nymphs fall to the ground and begin their 17-year life in the soil.
There is also a 13-year periodical cicada that is native to the eastern United States. There is still a lot to be learned about the why of the periodical cicadas.
The life cycle of most cicadas is significantly shorter, typically 3-5 years, but some may be longer, and they don’t usually all come out in a rush. They are often referred to as “annual” cicadas. Once the nymphs hatch from their eggs, they drop to the ground, dig down to the roots and attach to roots of desired plants, which may be trees, shrubs or grasses.
So, while the 17-year cicadas garnish a lot of public attention, there have been at least 21 species of cicadas identified in Idaho. The markings of the different species vary slightly, and the sound of the mating call can also help to differentiate them.
I recall the very vocal chorus of cicadas in Terreton, Idaho in 1989. The trees at the location were white willow and the noise level was enough to mask my tinnitus. I don’t know which species they were, but I was thankful for something that covered the ringing in my ears, even though it sounds a lot the same.
Idaho doesn’t get the mass of billions of cicadas that emerge with the various 17- or 13-year broods, but we can still get a pretty good chorus of cicadas in localized areas. It is common to hear them when you are doing your summer trail hikes. When you are out and about, enjoying nature, take a moment and listen for the cicada song.
Cicada make their mating calls by flexing a muscle on their body called the Tymbal Organ.
Basically the same mechanism as the metal clicker noise makers we play with.