Why Do Cicadas Sing?

Periodical cicadas, like these, remain underground
for years before emerging into the sunlight,
where they spend weeks calling for mates,
mating and laying eggs for the next generation.
CREDIT: National Pest
Management Association/Tom Myers

Why Do Cicadas Sing?
Apr 22, 2013 | Live Science | Elizabeth Palermo

What's black and red and heard all over? A cicada, of course.

The periodically appearing Magicicada, or 17-year locust, is due to rise up and break its silence along the East Coast of the United States this spring.

And as one of the world's loudest insects, cicadas are likely to make an entrance that will leave local ears ringing.

But why all the ruckus? After nearly two decades stuck underground, are these bugs making all that noise just for sheer joy? No: Cicadas, while mysterious, have clear-cut reasons for their unusual habits.

The chirping and clicking noises of the male cicada are actually a species-specific mating call that can be heard by females up to a mile (1.6 kilometers) away.

But with one estimate putting the number of cicadas at 1 billion per square mile, it's easy to understand why East Coasters might find this cicada serenade anything but romantic.

Male cicadas produce their calls by rapidly vibrating a white, drumlike plate, or tymbal, located on either side of their abdomens. A chorus of lovesick cicadas can reach volumes greater than 100 decibels, which is louder than a lawnmower at full bore.

Luckily for anyone needing a good night's sleep, these bugs usually cease their racket by sundown. The cicada's group chorus also repels birds that hunt by day, so when these insects stop singing, there's a good chance the birds have gone to bed.

And if you're on the East Coast, then you should get some rest as well, because this bug symphony is sure to last for several ear-splitting weeks.

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A storm is coming in the form of the 17-year cicada

© Photos.com

A storm is coming in the form of the 17-year cicada
Apr 2, 2013 | Michael Harper / RedOrbit

Every 17 years, the Eastern seaboard plays host to millions and millions of visitors who arrive with only one purpose in mind: to mate.

The Magicicada septendecim Brood II, or periodical cicada has an unusual life cycle and spends most of its days living underground, living on the bounty of tree roots. Then, when they near the end of their life, they emerge to breed and procreate. Very shortly afterwards, they die before returning to the ground, leaving a mess for any humans who live in the area.

The cicadas are expected to return to the surface once more this year, and public radio podcast Radiolab is asking for help to predict when to expect the cicadas.

Radiolab is turning this somewhat dire occasion into an opportunity for community science. The cicadas normally only emerge once the temperature reaches 64 degrees Fahrenheit. The resulting swarm is what Radiolab will be calling #swarmageddon, hashtag and all. When the temperature is just right, the cicadas will begin burrowing out of their holes 8-inches in the ground and start looking for mates.

While the cicadas are around, the males make a loud sound to attract potential partners. Once they complete their carnal tasks, they promptly die, leaving unsightly large piles of dead bodies all around.

"It can be like raking leaves in the fall, except instead of leaves, it's dead cicada bodies," explains Dan Mozgai, a cicada researcher with Cicadamania.com, speaking to National Geographic.

The Radiolab gang wants to know exactly when to expect #swarmageddon, so they're asking any and all to begin tracking the ground surface temperature 8-inches below the surface. To do this, they're sharing their plans to build an underground thermometer out of an Arduino kit, breadboard, a handful of resistors, LED lights, a thermistor, wooden dowel, and of course some tape.

The thermistor plugs into the breadboard and reports back to the Arduino board. The Arduino then triggers a series of LEDs which are also plugged into the breadboard. Civilian scientists can record their LED light patterns and feed them into the Radiolab Website to determine the temperature of the ground and report their data to the rest of the group. Radiolab will track this data and put it on a map so people around the world can see when the soil temperature finally reaches prime cicada weather.

According to Radiolab, after one week of steady 64F-and-up temperatures, the Cicadas will emerge and begin spreading their love up and down the Eastern seaboard from Connecticut to Virginia.

Some other interesting facts about periodical cicadas:

According to cicadamania.com, there are actually two types of periodical cicadas. The Brood II, which are expected this year, show up every 17 years. There are other broods, such as Brood XIX and Brood XIII which emerge every 13 years. According to Dan Mozgai, some scientists believe the cicadas emerge in 13 and 17 year cycles because these are prime numbers. This makes it difficult for predators to synchronize with the cicadas and learn to expect them on their cycles.

Cicadas also have five eyes. These insects have three ocelli, or little eyes, in between those two buggy compound eyes. It is believed that cicadas use these smaller eyes to detect light and darkness.

Finally, no creature gets to enjoy in a raucous mating free-for-all every 17 years without some consequence. Cicadas can contract a type of insect STD called the Massosporan fungus. This fungus infects and fills the cicada's abdomen; it will then begin to grow until the cicada's abdomen finally falls off. This fungus can infect entire colonies through mating.