This Morbid Fungus Turns Cicadas Into Hypersexual Zombies Without Genitals — A Biologist Explains

Forbes

06-04-2025

Massospora cicadina's lifecycle is so closely linked to periodical cicadas, that it waits 17 years ... More to hijack its sex life — then spreads by turning them into walking spore bombs.
Every 13 or 17 years, the forests of eastern North America erupt in a slow-motion frenzy. Billions of cicadas claw their way to the surface after spending nearly their entire lives underground, waiting for the moment to molt, mate and vanish.
For a few manic weeks, tree trunks drip with newly hatched adults, and the air rings with a chorus that can rival jet engines. But they're not alone.
Emerging with them — timed to the very year, to the very brood — is something far more sinister. This is a parasitic fungus called Massospora cicadina. A pathogen that infects these ancient insects and rewires their behavior, turning them into sexual decoys whose final acts spread spores like a plague.
Beyond the chaotic rise of every brood lies one of nature's most grotesque manipulations — a horrid affair that keeps this species alive against the odds.
The life cycle of Massospora cicadina reads like a precision-timed ambush. This parasitic fungus lies dormant underground for 13 or 17 years, synchronized perfectly with its host — the periodical cicada.
When broods emerge en masse, so does the fungus, triggered by the very same environmental cues that summon the cicadas from the soil.
Massospora infects its host in two distinct stages, according to a January 2018 study published in Scientific Reports. In the first, called 'Stage I,' cicadas emerging from the ground pick up resting spores, ready to infect others around them. Once these cicadas take to the skies, the fungus actively spreads from infected cicadas to healthy ones.
White fungal plugs burst from the insect's abdomen, shedding spores as the cicada continues to move, mate and interact, often without apparent distress. Later, in 'Stage II,' the fungus produces hardy spores that fall to the soil and lie dormant until the next generation surfaces, years down the line.
Among the stranger twists in Massospora's evolutionary arsenal is its probable chemical manipulation of host behavior. Infected periodical cicadas have been found to carry cathinone, a psychoactive compound that is chemically related to amphetamines, according to an October 2019 study published in Fungal Ecology.
This discovery marks one of the few known cases of a fungus producing such a stimulant. Researchers detected cathinone only during the active (conidial) phase of infection, when the fungus might be helped by its host staying mobile, sociable and — most critically — sexually active.
Though the exact biochemical pathways remain unknown, it appears Massospora may be chemically encouraging infected cicadas to keep flying, mating and thereby spreading the spores.
Unlike Cordyceps, which kills and immobilizes its hosts, Massospora keeps the lights on just long enough to turn cicadas into vessels of transmission. The cathinone doesn't seem to play a role in killing the insect directly, but it might be influencing its priorities until it dies.
If cathinone nudges infected cicadas toward hyperactivity, their sexual behavior provides the perfect delivery system. During the conidial phase, infected males flick their wings in a way that mimics female mating signals, attracting both uninfected males and females.
What the responding cicadas don't realize is that this apparent invitation comes with a fungal payload.
The infection is brutal but precisely targeted. The fungal plug replaces much of the host's abdomen, often destroying reproductive organs in the process. Yet despite this mutilation, infected cicadas continue to attempt mating.
Sexual signaling becomes a spore-spreading mechanism. Males try to mate with infected mimics, females are drawn in by the performance, and the fungus passes silently between them all.
This behavioral hijacking turns what should be a reproductive dead end into a superhighway for infection. This manipulation of courtship behavior is rare and unusually complex.
Even males missing their reproductive organs continue to call and copulate, seemingly unaware that their role has shifted from mate to vector. Healthy males, duped by the wing-flicks, attempt to mate and walk away carrying spores.
Females, too, are drawn into the cycle, often losing their genitalia during the act, sometimes left with pieces of fungal-infected tissue lodged on their partners. The choreography is grotesque, but efficient — an intricate, parasitic pageant engineered to keep the show going for as long as the fungus needs until the next brood comes along.
Some may find Massospora cicadina's behavior horrifying, while others might appreciate the ingenuity at play. Take this 2-minute quiz and see where you stand on the Animal Attitude Scale.