An absence of 17 years ends with a brooding presence.
Periodical cicadas belonging to what scientists designate as Brood II started emerging in Northeast Pennsylvania in the final act of a mysterious life cycle that began when most local students graduating from high school this month were still in diapers.
As of Monday, sightings of the large, red-eyed insects with orange-veined wings had been reported in Luzerne, Monroe and Pike counties. Wyoming County was expected to follow shortly.
Entomologist Greg Hoover, senior extension associate with Pennsylvania State University's College of Agricultural Sciences, said warming soil usually triggers the insects' emergence from their underground burrows.
When the soil 6 to 8 inches below the surface hits 64 degrees Fahrenheit, the cicada nymphs migrate above ground, often en masse, he said.
"What I have found through the years is overnight there is a little rainfall and - bingo! - it's a just a parade of these nymphs coming out of the ground," Mr. Hoover said.
Pennsylvania is home to eight different broods, or populations, of 17-year cicadas, each with its own timetable and distinctive geographic range. Brood II is expected to surface in Luzerne, Monroe, Pike, Wyoming and 13 other counties, all in the eastern half of the state.
Lackawanna County is not part of Brood II's range. The next 17-year cicada emergence in Lackawanna County will happen in 2021, when Brood X will appear.
Once above ground, cicada nymphs shed their exoskeletons and complete their transformation into creepy-looking, but harmless, adults. The males then begin their distinctive - and, depending on their numbers, sometimes deafening - serenade in an attempt to attract a mate.
Vincent Catrone, a forester at the Penn State extension office in West Pittston, said even people who don't see cicadas will know they're there.
"If people live near the woods, they will hear them in their backyard, and they can get quite loud," Mr. Catrone said.
Aside from the noise they make, cicadas tend to get noticed because they are large and have poor flying skills, which means they fly into things, including people, he said. While they can be a nuisance, cicadas are not a major pest.
After mating, female cicadas lay their eggs in slits in tree branches, where the nymphs hatch a few weeks later. The hatchlings drop to the ground and enter the soil, where they will feed on fluid from plant roots for the next 17 years.
Mr. Hoover said the public spectacle will be finished in a short three or four weeks.
"The periodical cicadas' activity will be over by the Fourth of July," he said.
Contact the writer: dsingleton@timesshamrock.com