A creature with one of the most unique life cycles on earth will be visible around Eastern Pennsylvania in the coming weeks.

The 17-year cicadas will emerge from the ground sometime around or after Memorial Day to complete a life cycle they began in 2004.

They should be seen, and heard, through most of the month of June - mostly during the warm daytime hours.

“People go across the world to see migrating wildebeest, and this is just as much a force of nature to see, even if you’re not into bugs. Kids will never forget it,” said Marten Edwards, Ph.D., chair of the biology department at Muhlenberg University in Allentown.

The 17-year cicadas are known for their unusual appearance, the zombielike exoskeletons they leave behind, and their distinct noise.

Usually, they appear in concentrated pockets. While some areas may see none, others will see thousands. Past cicada broods have impacted outdoor events and led to road closures due to slick conditions caused by thousands of bugs on the road.

“You’re going to see some large emergences in localized areas, depending on how many eggs hatch, how many were able to burrow into the ground,” said Franklin Klock, a naturalist at the Carbon County Environmental Education Center.

If you saw them last time …

The best predictor for where the insects will emerge is past records. Cicadas rarely move during their short adulthood. For the most part they emerge, reproduce and then die.

“What I normally tell people is if you had them 17 years ago, you’ll have them again. But if you didn’t have them, you probably won’t see a huge influx,” Klock said.

The cicadas set to emerge this year are known as Brood X. The name 17-year cicada implies that they’re only seen once every 17 years. But in reality a different “brood” emerges from their long hibernation most years.

Complicating things even more, there are also annual cicadas which emerge each year, albeit later in the season. Seventeen-year cicadas are gone by the end of June.

“These only take advantage of the early part of the summer before their specialized predators come out. By the 4th of July, you’ll be lucky if you hear a single cicada,” Edwards said.

In 2004, cicadas were sighted in areas across Pennsylvania and surrounding states. The largest number of recorded sightings were south of Carbon County, in areas near Reading and Montgomery County.

Edwards and his students tracked the location of “Brood X” the last time it emerged. They generated a lot of new data showing where the bugs could be found.

This time, Edwards and other biologists are expecting to gather even more data on the cicadas’ emergence, and they’re looking to regular people for help. A free app, Cicada Safari, allows anyone to report a cicada sighting. Biologists screen each submission to make sure it is accurate, and it’s added to a map within a couple of days.

Already, people have been submitting photos of cicada larvae emerging from their holes after 17 years underground.

Edwards said that the university’s 2004 research found that Carbon County did not have a large number of cicadas from Brood X. But it’s possible that the new data could document hatches that went undetected last time around. App users will be able to track them almost in real time.

Sightings to the South

The best place to see brood X cicadas will be south of Allentown, in Southern Lehigh, northern Berks and Montgomery counties, Edwards said.

The best way to find adult cicadas is by sound. Male cicadas produce a song to attract females. The noise actually comes from an organ on the males’ abdomens. Adult cicadas have no mouths, because they do not eat.

Seventeen-year cicadas can also be distinguished from their counterparts by their coloring. They have red eyes and a black body, while the annuals have a more green and brown appearance.

After nearly two decades underground, they spend just a couple weeks above the surface. Once they’ve laid eggs, they will die, and their young will return to the ground to begin the cycle anew.

“They have one of the shortest childhoods on earth, and one of the shortest adulthoods. It’s 17 years underground where they go through their adolescence,” Klock said.

Not all the cicadas which emerge from the ground successfully reproduce and lay eggs. The newly emerged cicadas are a favorite meal for animals including deer. The extra nutrition in the ecosystem actually means a healthier population for the animals which consume the cicadas.

There are even groups of people who enjoy cooking with the insects.

The females will damage the tips of tree branches when they lay their eggs, but it can actually have a natural pruning effect.

The cicadas have other benefits for the environment as well. Their skeletons are a natural fertilizer.

“If you’re worried about the mess, they make wonderful fertilizer. There’s always a rush of growth in the forest after the cicadas. They get all that free nitrogen fertilizer,” Edwards said.