An emerging cicada nymphs from Brood XIV , the 17 - year variety, at Ostego Park in Dix Hills.. (Bill Davis, Newsday / May 20, 2008)After 17 years underground, the cicadas of Brood XIV are tunneling to the surface in preparation for their ear-splitting Suffolk County debut.
But even as dime-sized cicada burrow holes appear in Dix Hills and East Setauket, scientists wonder if this year's group will emerge in full, raucous force.
Loud but harmless, Long Island's smaller periodical cicada broods have been in decline in recent years, a trend some attribute to suburban development. And the cool, wet spring could mean trouble even for Brood XIV, the largest of the five historically found here.
"They need nice, sunny, warm weather to reproduce," said Chris Simon, a University of Connecticut professor who has studied cicadas on Long Island since 1974.
Often mistaken for locusts, periodical cicadas do not eat crops and are unlikely to damage cultivated gardens. They spend most of their lives below ground in parts of the Northeast and Midwest, sipping sustenance from tree roots. Some have 13-year life cycles, others, such as Brood XIV take 17 years to mature. They then leave their burrows en masse for an epic wave of courtship, sex and death.
Scientists expect Brood XIV to emerge here in the next few weeks.
Magicicada septendecim, the type of periodic cicada found on Long Island, is one of only seven cicada species that have synchronized development. Unlike the annual cicadas that sing out each summer, these cicadas are born together and mature in lockstep. Their reproductive success depends on bursting from the soil in such large numbers that predators, such as ground wasps, become satiated.
During Brood XIV's last local appearance in 1991, cicadas were reported in nearly a dozen neighborhoods across Huntington, Smithtown and Brookhaven towns. But the 2004 emergence at Connetquot State Park of their cousins in Brood X -- the smallest of the Long Island groups -- lasted only days.
"They were eaten by birds within a week," Simon said. "When the population size gets lower, then they're more susceptible to being wiped out by birds and bad weather."
Scientists think the insects have an inborn molecular clock that tells them when the correct number of years has passed. They emerge after the soil warms to about 64 degrees. After molting, males gather in "chorusing trees" and lure females with courtship songs that some have likened to the winged cacophony from Alfred Hitchcock's "The Birds."
Cicada emergences on Long Island tend to be more patchy and localized than in other parts of their range, such as Ohio or Kentucky. But local clusters of the insects can be just as dense -- and as loud, said John Cooley, a University of Connecticut scientist working on an updated map of cicada distribution across the Northeastern U.S. American cicadas normally sing during the day, but on very hot nights when clusters are very dense, some males may burst briefly into song.
A mass emergence of periodical cicadas can alarm those who find their yards suddenly swarmed by hundreds of orange-striped flying insects.
Rest easy. Cicadas don't sting or bite and they won't hurt most plants, said Thomas Kowalsick, a horticulture consultant at Cornell Cooperative Extension of Suffolk County.
Experts advise against spraying pesticides in an effort to stem a cicada emergence. "It doesn't do much good, and it poisons your yard," Simon said.
While females gnaw holes in tree branches to deposit their eggs, healthy adult trees should be able to withstand the damage. Kowalsick advises those concerned about their newly planted young trees to cover them with mesh netting.
Cicadas may even benefit your garden -- one study found the decomposing corpses of adult cicadas act like fertilizer to enrich the soil.
That's just one of many roles cicadas play in their lifetimes.
Birds tend to produce more young after an emergence because they've had more food. Young nymph cicadas are food for ants and other creatures that aerate the soil. As they grow, cicadas sustain larger burrowers: "You always see an increase in moles the last couple years before an emergence," Simon said.
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jennifer.smith@newsday.com
