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Huge numbers of cicadas set to emerge

Monday, April 29, 2013
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A cicada.
A cicada.

— An enormous brood of locust-like insects is poised to emerge along the East Coast within the next few weeks, after spending 17 years underground.

They’re predicted to be so numerous that in some locations hardly a leaf will be free of the large, black, red-eyed, flying creatures. And where their concentrations are high, the males’ mating calls might well be compared to a chorus of buzz saws.

The emergence could resemble a plague, but experts say the insects — known as periodical cicadas — don’t cause much in the way of damage and are actually a valuable part of the ecosystem.

The group preparing to make its above-ground debut is called Brood II. Its territory stretches from southern Albany County all the way down to northern Georgia.

Brood II will fly for between four and six weeks, likely beginning in late May, with the peak occurring around the first week of June, said Timothy McCabe, New York’s state entomologist.

The insects, which are about 11⁄2 inches long, will emerge well in advance of the dog-day cicadas commonly heard buzzing in Capital Region trees during July and August.

“The dog-days, they’re solitary. You hear one in the treetops, and then you’ll hear another one a half-mile away, that sort of thing. It’s not spectacular at all like the periodical cicada is,” said McCabe.

The cacophony created by a large group of male periodical cicadas all buzzing at once is tremendous — like being near a saw mill with several saws going at once, he said.

Their choruses can reach 80 to 90 decibels, said Cole Gilbert, an entomologist at Cornell University.

“We’ve got a noise ordinance in Ithaca that you can’t be louder than 90 decibels,” he noted.

Cicadas spend most of their life underground as nymphs, where they subsist on sap sucked from tree roots. Once they reach adulthood, which takes from 2 to 17 years, depending on the variety, they tunnel out of the soil, shed their exoskeleton, and mate.

Females then cut slits in twigs and deposit their eggs inside.

When multitudes of slits are cut in the branches of saplings, it could damage or even kill a very young tree — a cause of concern for some orchard owners, McCabe noted.

Netting placed over branches of trees before the emergence occurs can protect them, Gilbert said.

When the cicada nymphs hatch, they drop to the ground and burrow in and the life cycle begins again.

The insects only feed while in the soil, noted George Robinson, associate professor of biology at the University at Albany.

“I don’t think they do that much damage, but they certainly spend a lot of time sucking the juice out of roots,” he said.

Luis Pabon, technical director of Catseye Pest Control, said he anticipates a barrage of calls from homeowners wondering what to do about the insect invasion.

There’s not much they can do to get rid of cicadas, he said.

“If they can deal with the noise, it’s only a matter of time before they wind up dissipating on their own,” he commented.

Cicadas don’t bite, Gilbert noted.

“They annoy people because they’re loud, especially if there’s a big aggregation of them calling. That bothers people. They bump into you; they’re not very good fliers. So that bothers people too,” he said.

Brood II’s emergence will be a welcome occurrence for animals, including birds, raccoons, foxes, shrews and squirrels, which will feast on the flying insects.

“There’s reasonable data from red-winged blackbirds and eastern bluebirds that in a cicada year, they fledge more young and the young are heavier,” Gilbert said.

The cicadas that aren’t consumed will feed the soil when they die.

“It’s a big pulse of nitrogen fertilizer that goes into the soil, and that’s been documented, that nitrogen is in higher concentration in the soil after cicadas have died there,” Gilbert said.

Gilbert, who has studied cicada populations, found that one pocket of Brood II, which used to emerge in Connecticut and Rhode Island, died out sometime between 1954 and 1971. A second pocket, which 100 years ago stretched across the Finger Lakes region, is dwindling.

According to McCabe, entire broods have disappeared over the years. There used to be 17 in eastern North America and now there are 15, he said.

The reason for the decline is unclear. McCabe said he attributes some of it to loss of habitat, while Gilbert speculated that biological factors could also be a culprit.

“Their whole success is based on the concept of satiating their predators. Millions of individuals come out in a couple of weeks; everybody gets so full they can’t eat another bite and that allows the rest of the brood to get through and reproduce,” Gilbert explained.

Once cicadas’ numbers begin diminishing, predators can take bigger bites out of the population at each emergence, eventually whittling it away.

Climatic factors could also be coming into play, he speculated.

 
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