Friday, April 30, 2004
These insects are harmless to people and vegetable and flower gardens.
By PETER H. MILLIKEN
VINDICATOR STAFF WRITER
MERCER, Pa. -- The forest will be abuzz when the world's longest-lived insects emerge here later this spring.
Experts predict Mercer County residents will see the emergence of the 17-year cicadas from the ground in late May or early June.
"They'll get to witness one of the most amazing biological phenomena. Thousands, or maybe millions, of these insects emerge," said Ray Novotny, naturalist at Mill Creek Park in Youngstown.
"They can expect a lot of noise and a lot of singing insects," said Norman C. Kauffman, a Pennsylvania Bureau of Forestry entomologist. He was referring to the eerie-sounding mating song the males sing.
"It's amazing that these things are in the ground feeding for 17 years, and then, by the millions, they can emerge," mostly within a few days of one another, he said.
Coming up
For 17 years, the nymphs are between 2 inches and 2 feet underground, sucking nutrients from tree roots. Then, they surface through half-inch holes in the soil, climb up trees, discard their shells and become adults, according to a Penn State University news release. The adults are about 11/2 inches long and have reddish orange eyes and orange wing veins. Periodical cicadas are found only in North America.
Their emergence begins when the soil temperature reaches about 65 degrees, according to the book, "In Ohio's Backyard: Periodical Cicadas," by Gene Kritsky, published in 1999 by the Ohio Biological Survey.
"These insects are harmless to people. They do not bite or sting," said Greg Hoover, a Penn State entomologist.
They also won't harm vegetable or flower gardens, and they cause minimal damage to mature trees, Kritsky said in a telephone interview.
However, he recommended bagging young trees less than 6 feet tall with screen netting or loosely wrapped cheesecloth to prevent the females from damaging the trees by laying their eggs in the branches.
Recorded emergence
USDA reports show a 17-year cicada emergence in the Borough of Mercer in 1902, but they don't record any before or since then, said Kritsky, a biology professor at the College of Mount St. Joseph in Cincinnati.
However, Kauffman said he saw cicadas in the Lake Wilhelm area of Mercer County when they emerged in 1987, and Penn State officials show Mercer County as a place where 17-year cicadas will emerge this year.
In this year's emergence of cicadas from Brood X -- the largest brood in the nation -- Mercer County is an "island of cicadas," and nobody knows why, Kauffman said.
None of the surrounding counties is scheduled for an emergence this year. The surrounding counties experienced an emergence of a different 17-year cicada brood two years ago.
Heavy concentration
Brood X, which is spread through portions of 15 states and is known as the great eastern brood, is heavily concentrated in eastern Pennsylvania and central and southern Ohio.
After their emergence, the adults will live for only about a month. But six or seven weeks after the eggs are laid, nymphs will hatch, drop to the ground and enter the soil, where they'll remain until 2021, Penn State officials said.