A cicada rests on a branch near Chicora.

This is an excerpt — pick up Friday’s Butler Eagle to read the full article.While many thought the 17-year magicicadas that arrived 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 have been 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 the another.Such is the case in East Butler, where the eastern end 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,” which has been likened to the sound effects used to signal an approaching alien space ship in 1960s science fiction movies, can be deafening as millions of the insects call simultaneously for a mate.They have unexpectedly made their home in many northern neighborhoods, such as Chicora and West Sunbury, when maps of “Brood VIII” show them coming out from the middle of the county and south.Michael Skvarla, the director of the insect identification lab at Penn State Extension headquarters in State College, Centre County, said many factors weigh into the distribution of the cicadas.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.