While many thought the 17-year magicicadas that emerged three weeks ago from below the Earth's surface would cover trees, sheds and porches in the southern part of the county, the harmless thumb-sized bugs are actually sporadically distributed throughout Butler County.

No maps are available of the specific locations of the cicadas in Butler County, but they might cover a property on one side of a municipality and nary a red-eyed representative can be found on another.

Such is the case in East Butler, where the eastern end of the borough near the Butler Hunting and Fishing Club is polluted with cicadas, while the western area near the ball fields is devoid of the cyclical bugs.

Their distinctive “song” — often likened to the sound effects used to signal an approaching alien spaceship in 1960s science fiction movies — can be deafening as millions of the insects call simultaneously for a mate.

The invaders from below unexpectedly made their home in many northern neighborhoods, such as Chicora and West Sunbury, but the projected maps of “Brood VIII” showed them coming out from the middle of the county and south.

Michael Skvarla, director of the insect identification lab at Penn State Extension headquarters in State College, Centre County, said several factors weigh into the distribution of the cicadas. Those factors include the type of trees in the area where eggs were laid 17 years ago, whether larva underground was killed by soil excavation or logging activities that eliminate the larva's main food source: tree roots.

“We don't think about what we are doing above ground,” Skvarla said. “That it is affecting insects underneath.”

He said larva also favor soil in some areas over others.

“It makes it so that they are patchily distributed when they do emerge,” Skvarla said.

He suspects the cacophony will last another couple weeks, when the cicadas will lay their eggs on the trees, weaken and die.

“The forest creatures will have a feast,” Skvarla said of the millions of cicada corpses soon to litter lawns and forest floors. “Raccoons, opossums, skunks and other creatures will eat them.”

Skvarla explained how scientists separated all cicadas into broods and numbered them with Roman numerals, so they know where and when each brood will make an appearance. He added that the local brood is fairly small compared to other broods throughout the state.

Brood VIII appeared in Pennsylvania as far east as Indiana County and west to towns in extreme eastern Ohio, according to Skvarla. Some cicadas also appeared in the tip of the West Virginia panhandle.

But Skvarla said no other broods will appear in Butler County until Brood VIII returns again in 2036.

He urges residents to enjoy the phenomenon, as it only occurs for a short time.

“It's not something you see every day,” Skvarla said. “Soon enough, they'll be done and you won't have to deal with it again for almost 20 years.”

Mary Reefer, a Penn State Master Gardener who lives in Franklin Township, is more than a little disappointed that not one cicada has emerged on or near her Mount Chestnut property.

She said they will pretty much emerge in exactly the same locations in 2036.

“In 17 years, I expect to be disappointed again on our farm,” Reefer said.

She explained that instinct tells the cicadas to emerge from their brown shells once they come out of the warm soil and begin to crawl. They often cast off their shells on the ground or in the trees.

They then sprout wings and head to the very top of a plant, bush, tree or structure to get as high as they can to avoid predators.

“That's when they'll make themselves known (by singing),” Reefer said.

After mating, the females lay their eggs on the tree or structure they have climbed. Once hatched, the eggs fall to the ground and burrow in, according to Reefer.

“They have no means of moving, so where they lay is where they'll fall is where they'll come back in 17 years,” she said.

She hopes residents who are not fans of the rare cicadas have come to at least appreciate them.

“I think people realize now that they didn't destroy their gardens or chew up their orchards, but they are an interesting phenomenon to witness,” Reefer said.

Pat Trinidad, who lives on 60 acres in Middlesex Township, said she does not consider the cicadas a nuisance since they come every 17 years and then only for six weeks or so.

“But they're noisy,” she said. “The noise is almost deafening in the woods.”

Trinidad said the bugs were worse at her cabin in Knox, Clarion County, around Memorial Day, but had yet to emerge in Middlesex at that point.

“When we went up there right before Memorial Day, they were everywhere,” Trinidad said, “on the outside furniture and on the ground.”

She said she watched the nymphs emerge from pencil-sized holes they had excavated to escape their subterranean world. She said the phenomenon of nymphs knowing when to emerge is fascinating.

Trinidad said while she is not a fan of insects, she doesn't hate the cicadas.

“I'm not glad I got them, but it doesn't bother me, either. “It's just something new,” Trinidad said. “It's amazing that every 17 years, they come.”

Trinidad's granddaughter is a much bigger fan.

“She is afraid of spiders, but when she sees a cicada, she says, 'Oh look, how cute,'” she said. “I don't think they're cute at all.”

Experts say once the cicadas begin weakening in anticipation of their death, which will occur in a few weeks, they will lose the ability to fly successfully.