From Smithsonian Magazine's blog (http://blogs.smithsonianmag.com/smartnews/2013/03/after-17-years-the-northeast-is-about-to-be-blanketed-by-a-swarm-of-cicadas/)
"A mass of winged creatures, red eyes glowing, the cicadas “are expected to emerge and overwhelm a large swath of land from Virginia to Connecticut — climbing up trees, flying in swarms and blanketing grassy areas so they crunch underfoot,” says http://www.wnyc.org/articles/wnyc-news/2013/mar/11/cicadas-are-coming/.
|Great Plains Nature Center|
They live in the ground and eat tree roots, emerge when the soil 8-inches below the surface is 64 degrees. Then they molt, mate and lay eggs. The nymphs crawl underground and emerge in 17 year cycles. They are noisy but to not bite or sting.
Want to know more? Here's the OK State University Fact Sheet on them
The PA State Fact Sheet is at http://ento.psu.edu/extension/factsheets/periodical-cicada
Thanks to the PA Master Gardeners' blog for the tip - http://franklincountymgs.blogspot.com/.