Cicadas, They're Back! Get Ready for the Invasion

By Linda Lombardi | vetstreet.com

Photo courtesy of the Indiana Academy of Science If you live in the Northeast, soon you'll be hearing the drone of periodical cicadas. They've been living underground for 17 years. Now they're back, and they've got one thing on their mind - finding a mate.

What's That Noise?

The male cicadas make the distinctive noise with an organ under their wings called the tymbal, which is sort of like a drum pad. "Basically the calling attracts the cicadas to the treetops," says Michael Raupp, professor of entomology at the University of Maryland, who has a website called Bug of the Week. "It's a way for them to aggregate. They're saying, 'Party up here!'"

It may be music to their ears, but to us, not so much. In fact, the group call is so similar to the sound of machinery that even the cicadas are sometimes fooled. "Leaf blowers, weed whackers, even some riding lawn mowers send out vibrations that trigger the same response, and the males will swarm users of these power tools," says Gene Kritsky of the College of Mount St. Joseph, author of two books about cicadas.

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Once the party's gathered - ideally in a tree rather than on a mower - the male has three more types of calls that he uses to woo a potential mate. There are three species of 17-year cicadas that emerge simultaneously, so the first call is to make sure she's the same species. "The first call is like 'Do you come here often?'" Raupp says. "The second is 'That's a lovely dress,' and the third is 'Let's go back to my place.' If she's impressed, she'll respond with a little dance and clicking."

A Magical Life Cycle

We see periodical cicadas more often than every 17 years because there are 12 groups, called broods, and their emergence is staggered. There are also three broods of 13-year cicadas. Seventeen-year and 13-year cicadas will emerge at the same time once every 221 years.

Cicadas that appear every year are found all over the world, and those are the ones you hear later in the summer. But periodical cicadas only occur in eastern North America, and their life cycle is unique in the animal kingdom. It's so amazing that it's even reflected in their Latin name, Magicicada, which was given to them, Kritsky says, because "it tied into the fact that their life cycle is almost magical."

Kritsky has researched this life cycle back to the first written evidence of European settlers' encounters with these insects in the 17th century. Earliest formal scientific descriptions began a long tradition of confusing cicadas with another insect that appears in massive swarms.

Cicada or Locust?

Paul Dudley first saw periodical cicadas in 1699, and when he saw them again in 1716 he wrote up a paper. But, Kritsky says, "he wanted to make sure it was right, so he waited another 17 years." However, when Dudley finally sent his manuscript to the Royal Society in London, it had one big error: He called the insects locusts. When they wrote back to correct him, he was unconvinced. "He said he showed them to a reverend who said that definitely they were the locusts eaten by John the Baptist," Kritsky says.

The society arranged for a real locust to be sent from Cairo to Boston so that Dudley could compare. His mistake was obvious because the two insects don't have a lot in common except for the fact that a whole bunch of them appear at once. That's a strategy called "predator satiation."

"If you've ever been in the midst of a big emergence, you see literally everything eating them: raccoons, birds, dogs, cats. It's like walking outside and the whole place is being inundated with flying Hershey's Kisses," Kritsky says. "That's part of the cicada survival strategy: Everything out there can eat their fill of them and there's still millions left."

At Risk: Trees and Weddings

It may seem like a plague, but cicadas can't hurt you. Young trees are about the only thing they can damage, by laying too many eggs in their delicate branches. Cicadas emerge based on soil temperature, and Kritsky is developing a way to predict the date from the weather forecast, so tree plantings can be scheduled to avoid them.

There is one other problem Kritsky says he gets asked about: "I also help plan a lot of weddings." Unlike tree planting, though, people tend to want to schedule a cicada-free outdoor wedding a year in advance, so all he can do is supply the historical averages. He notes that these have moved about a week earlier in the last half century, due to warmer springs.

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What's on the Menu?

You don't have to worry much if your pets are just as attracted to the flying buffet as wild animals are. Cicadas in moderation aren't going to cause a problem. Although, like anything else, be careful of overindulgence.

"If they eat enough of them, we could see some stomach upset, either vomiting or diarrhea," says Dr. Tina Wismer of the ASPCA Animal Poison Control Center. Dogs and cats can't digest the crunchy exoskeletons, so in excess they could theoretically cause an obstruction, but typically they're just going to pass in the stool.

In fact, even humans can eat cicadas. "I've eaten a lot of them," Raupp says. "They taste like a shellfish when boiled, and delicate and nutty when raw." His department even provides a collection of recipes at newsdesk.umd.edu.

If you're brave enough to try it, look for the white, newly emerged adults, before they harden and darken. "The nymphs leave the soil, climb a tree, and split their immature skin and a white adult emerges, then over the next hour and a half slowly turns dark," Kritsky says. "It's really cool to watch."

Also stick to females, he says: "Females are full of eggs, and that's where the flavor is. The males are essentially hollow in the abdomen because they use that as a resonance chamber." But be careful if you have shellfish allergies because cicadas are also invertebrates.

Kritsky has found what might be the oldest published cicada recipe, from the Cincinnati Enquirer in 1902, for periodical cicada pie. But when asked how he likes his prepared, he says, "I don't look forward to eating them, because I love them too much.

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