Tens of thousands of people are participating in an unprecedented crowdsourcing event this summer to track the largest emergence of cicada in the country, especially in Montgomery County, writes Meryl Kornfield for The Washington Post.

Three cicada species (Brood X) burrowed underground for 17 years. They are appearing in the coming months.

Fans have emerged with the cicadas, in new Facebook groups, merchandise websites, community art projects, crowdfunded books, and more.

Researchers at Mount St. Joseph University in Cincinnati developed the Cicada Safari app to track the insect.

App users can share photos and videos. They can also dot a map with green pins to mark sightings. The app’s data from users potentially gives a comprehensive look at the cicada tsunami.

This could help scientists better understand ways that urban development may contribute to the insect’s decline.

It could also explain why they emerge in unusual 13-year and 17-year intervals. The interval is a strange mating schedule that still puzzles entomologists.

“This is incredibly useful for scientists, as well as a lot of fun for getting the general public out to witness one of the most spectacular natural events on planet Earth,” said Mike Raupp, an entomologist at the University of Maryland. “It’s cool in all regards.”

Read more about Brood X cicada in The Washington Post.