Community Corner

Summertime Song of the Cicada

These noisy insects have a fascinating lifecycle.

In late summer, the rasp of cicadas is so common, it becomes background noise. But the insects making those rattling hot-weather calls are highly adapted, fascinating creatures.

What it is: The cicada is a widespread insect, with thousands of species worldwide and more than 100 in North America. While they’re sometimes referred to as locusts, they actually belong to a totally different order of insects.

Cicadas create their creaking, rattling call – sometimes deafening at this time of year – differently than many other singing insects. Instead of rubbing body parts together like crickets, the male cicada instead tenses and relaxes muscles in specialized sections of the thorax called tymbals. He can do so rapidly enough that the push-and-pull of the tymbals sounds like a series of rapid clicks, amplified by hollow chambers in the cicada’s body.

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Nearly all cicadas have multi-year lifecycles, with juveniles – called nymphs – living out most of their lives underground, feeding on roots.

After two, five or even 17 years, the nymphs dig themselves out and molt one last time, taking their adult winged form and beginning the work of finding mates to start the cycle over.

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Species with shorter lifecycles, like the so-called “dog-day cicada” of genus Tibicen that we hear outside now, generally hatch out yearly.

But the much longer-lived species of genus Magicicada have synchronized broods, which means millions of individuals in a specific geographic area hatch out together at 13- or 17-year intervals. (Possibly the world’s biggest Magicicada brood hatched this year in the southern U.S.; a 17-year brood emerged a few years ago in New Jersey and parts of the Midatlantic.)

Synchronized broods are an effective evolutionary adaptation, and not just because emerging in great numbers reduces the risk for each individual cicada of becoming a predator’s lunch.

In the broad scheme of things – we’re talking millennia – having a much longer lifecycle than your most common predators means those predators won’t be able to rely on you as a food source, and will have to develop a closer prey relationship with other species. 

Where to find it: Unless you’re in the midst of a Magicicada brood emergence, when you literally have to beat the bugs off you, you might have trouble actually laying eyes on a cicada. They tend to be heard, but not seen. 

But getting a closer look is fun. Try scoping out a likely tree during the day, preferably one where you can hear lots of cicadas singing or where you can see abandoned nymph exoskeletons. Return at dusk or after dark with a flashlight and examine the ground under the tree to keep an eye out for emerging nymphs, which look a bit like giant fleas. 

If you’re lucky, you’ll catch a nymph clinging to the tree and shedding its dry shell to take its adult form.

Why bother. Cicadas’ amazing lifecycle isn’t unusual in the insect world, but because cicadas are big, noticeable bugs that live all around us, we can get a front-row seat to the spectacle of their emergence year after year.


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