Researchers are crawling through many of the nooks and crannies of the largest known cave system in the world in an effort to better understand what’s happening with more than 100 different cricket species. Mammoth Cave, much of which snakes underneath parts of the eponymous national park in central Kentucky, has more than 400 miles of surveyed passageways. Many of these spaces are filled with crickets, and National Park Service researchers are tracking these insects, a keystone ecological indicator, as a way to monitor the health of the cave system. According to one researcher, numerous animals feed on the crickets’ dead bodies, eggs and a fungus that grows on their feces. While cricket numbers have fallen in past decades, surveys show they seem to have stabilized more recently.