After 17 years underground, the Brood X periodical cicadas are slowly emerging in 15 states across the East Coast and Midwest.
They'll shed their skins and spend four to six weeks mating before the females lay eggs and they all die.
But some of them are getting wilder in their short lives above ground.
A fungus called Massospora, which can produce compounds of cathinone — an amphetamine — infects a small number of them and makes them lose control.
The fungus takes over their bodies, causing them to lose their lower abdomen and genitals. And it pushes their mating into hyperdrive.
"This is stranger than fiction," Matt Kasson, an associate professor of forest pathology and mycology at West Virginia University, tells NPR's All Things Considered. "To have something that's being manipulated by a fungus, to be hypersexual and to have prolonged stamina and just mate like crazy."
Kasson, who has been studying Massospora for about five years, says just before the cicadas rise from the ground, the spores of the fungus start to infect the bug. Once it's above ground and starts to shed its skin to become an adult, its butt falls off.
Then a "white plug of fungus" starts to grow in its place.
"It looks as if the backside of the cicada is being replaced either by chalk or by like one of those nubby middle school erasers," Kasson says.
The insects have no idea what's happening. The fungus, however, is "pulling the strings" and making the cicadas want to mate with everyone.
Males that are infected will continue to mate with females, but they'll also pretend to be females so they can spread the fungus to even more partners.
"It's sexually transmissible," Kasson tells NPR. "It's a failed mating attempt, of course, because there's no genitalia back there."
The fungus causes different reactions in different types of cicadas. Periodical cicadas, which take more than a decade between appearances, get sex crazy from cathinone. In yearly cicadas, the fungus makes them instead become hypersexual from psilocybin — the same chemical found in psychedelic mushrooms.
Kasson estimates Massospora probably infects fewer than 5% of cicadas. And as far as he knows, the bugs are not in any pain.
"Everybody's having a good time while they're infected," he says. "So I don't imagine there's much pain — maybe a desire to listen to the Grateful Dead or something like that, but no pain."
Karen Zamora and Courtney Dorning produced and edited the audio story.