Sex invades the treetops

Sun Staff

The "song" of the 17-year cicada has crescendoed to the proportions of a "din," or at least a "racket" in Central Maryland; cats and dogs are snacking on them like potato chips and their discarded shells and rotting bodies are piling up.

If all this is driving you buggy, experts say, about all you can do is turn up the stereo, sweep the walk and wait them out.

"I think it's peaking right now," says Gaye Williams, a Maryland Department of Agriculture entomologist, who is in the throes of a certifiable love affair with the insects.

"The volume in my yard went up Saturday morning, like they had kicked in the big speakers," Williams says, confessing to having audiotaped the cicadas' noisemaking and to shooting eight rolls of film of their transformation from nymphs to winged adults.

"I'm totally intrigued," she admits. She even plans to videotape their mating ritual in a sort of cicada-porno movie.

Sex, after all, is what all the noise in the treetops is about. The male cicadas are frantically calling to the females, desperate to mate before their biological clocks – with only weeks to tick – run down.

Cicada-phobes may want to listen from a well-screened porch, but if you don't mind cicadas landing on your shirt or crawling up your leg, Williams insists you can learn a lot by joining the cicadas in the yard.

First, pick one up. If it protests with a buzz, it's probably a male. Under its wings, you'll see a small white circle about where you would expect its kidneys to be. That's the tymbal; the cicada vibrates it with muscles. That – multiplied by the millions – is what makes all the noise.

Marylanders are describing the cicada's love song in bewildering variety. Some say it's a high-pitched warble that sounds like the landing of a flying saucer in a grade-B movie, or an urgent, midrange rasping like some kind of out-of-whack machinery.

The variety in the descriptions, Williams says, is probably because there is not just one, but three, species of 17-year cicadas out there, each trying to be heard over the others.

The largest in both size and numbers is the Magicicada septendecim. He's the one making the constant flying-saucer sound. The adult is distinguishable – barely – by a brown plate between the base of the wings and the eyes.

The second species is the Magicicada cassini. "That's the one that has the shrill sound, like a horde of parakeets. It's much louder than septendecim," Williams says. It is distinguished by solid black plates between wings and eyes.

The third species is Magicicada septendecula, which also has the solid black plates, but has a striped belly to distinguish it from cassini. Williams believes their song may be the ticking noise she had heard in the treetops at noontime.

What the cicadas are busy doing now is sorting themselves out by species, Williams says. Alternately calling to the females and flying out from the trees, the males are locating the females and congregating by species in certain trees, or parts of trees, for mating.

"Fortunately, the bugs know the difference," Williams says. "I have to identify them just when I get ready to off them."

The mating ritual itself is not unlike that of humans, apparently.

Says Williams: "The female is cool to the whole thing. The male extends his closest front leg and they end up back-to-back."

The cicadas' song, generally, lasts from dawn until dusk, although a few individuals can be heard squeaking or singing "phaaa-roah, phaaa-roah" in the low bushes anytime during the night, Williams says. And a loud noise, such as a car ignition, may stimulate a competitive chorus from nervous males in the area.

But, ever protective of the cicadas, Williams declares their nighttime vocalizing is "not as obnoxious as some mockingbird getting up at 3 in the morning."

What might be obnoxious, however, is the smell of deepening piles of cicada carcasses, which began with nymphs that failed to emerge successfully from their shells and will grow as more of the billions of adults mate, lay their eggs in the branches, die and fall fluttering to earth.

To Williams, it is a nostalgic odor. "The smell brought back 1970 [the year of the cicadas' last emergence] to me," she says.

But to those less appreciative, she says that "when the flesh flies and the blow flies really start to work on them … that's going to knock it down quite a bit."

Her best advice is to rake up the carnage and bury it in the garden. It's good compost. The nymphs' empty shells, by the way, don't smell, and they can be returned to the soil, too.

Area cats and dogs, meanwhile, are doing their best to rid the world of cicadas.

"They're fascinated by the movement and the crunchy taste," says veterinarian Bill Benson, of the Falls Road Animal Hospital. He says his office receives 20 to 25 calls a day from people whose dogs are "eating them like crazy. They're like potato chips; it seems like one is not enough."

One caller reported his black Labrador had eaten at least 50 cicadas, then vomited and didn't eat again for several days.

But that seems to be the pattern. No fatalities and no toxic effects have been reported, only vomiting and gastric irritation. Mostly, vets agree, the cicadas are a harmless protein supplement.

If you haven't heard any cicadas in your neighborhood, it does not necessarily mean you live on the site of an abandoned toxic waste dump.

First, if you live in the northern reaches of Maryland, the cicadas may only now be tuning up. The phenomenon moves north with the hot weather.

Second, unlike ants, cicadas simply aren't everywhere, Williams says. You also may not have any cicadas if you have no trees, or if the soil in your yard was disturbed while the nymphs were living underground.

And third, areas barren of cicadas are colonized very slowly. "They don't seem to do much migrating. None of the old reports talk about them flying more than a mile and they only have every 17 years to make the jump," Williams says.

Which raises the ultimate cicada questions: Why 17 years? And why cicadas?

Nobody knows for sure why these cicadas have 17-year cycles. But among the theories is one which reasons that because 17 is a prime number – evenly divisible only by 1 and itself – Magicicada septendecim's cycle is less likely to intersect with that of a threatening predator or competitor.

For example, an 18-year cicada's cycle might intersect with predators or competitors with cycles of two, three, six or nine years, increasing the threat to the species.

Interestingly, Williams says, there are three species of cicadas in the Southern states that are virtually identical to the three 17-year species, except that their cycle is 13 years. Thirteen also is a prime number evenly divisible only by 1 and 13.

The ranges of the two sets of cicadas overlap in some areas, but the danger of competition is minimal because – thanks to the prime numbers – the two cycles coincide only every 221 years. The last time the two emerged together was in 1970. They won't meet again until 2191.

As for the cosmic question of why cicadas exist at all, Williams tells of the woman who called to ask how she could get rid of the miserable creatures, which appeared to her to serve little purpose other than to annoy people.

If their life cycle is too long for them to be a reliable food source for other creatures, what purpose do they serve in nature?

"It depends on your religious upbringing," Williams says, "whether everything in nature serves a purpose or whether they just belong to the cosmos.

"These guys accomplish what they are here to do – to preserve the species," Williams says she told the woman. "She didn't want to hear that we [humans] are a major annoyance to a lot of other species, too."

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