When billions of cicadas emerge from the ground this spring, many will be the unwitting hosts of a fungus that eats them from the inside out and turns them into sex-crazed zombies.
For the first time in 221 years, two cicada broods are expected to emerge simultaneously this spring in 17 U.S. states spanning the Southeast to the Midwest. After spending a respective 13 and 17 years underground, they have one mission: find a mate—then die.
But as scientists have learned from previous emergences of periodical cicadas, the parasitic Massospora fungus is waiting to infect them, take over their bodies, and keep them just alive enough to spread the disease to their mates during reproduction.
National Geographic spoke to one of the leading scientists researching this killer for a 2021 episode of our podcast Overheard at National Geographic. Here’s what National Geographic Explorer Matt Kasson had to tell us about how cicadas become “flying saltshakers of death.”
What does the fungus do to cicadas?
You can easily tell when a cicada has been infected by the Massospora fungus. It takes hold of the insect from the bottom and fills its abdomen with spores—leaving a telltale mark as it eats its way up.
(This deadly fungus is hitchhiking its way across the world.)
“It’s chalky white,” Kasson told us. “It’s either like a middle school eraser or like a math teacher’s chalk, so it’s definitely noticeable that something’s wrong with the backside of the cicada.”
Eventually the fungus destroys the entire lower half of an infected cicada. From there, said National Geographic podcast host and senior features editor Peter Gwin, “It only gets weirder. The fungus is extra devious. Not only does it make the cicadas waste away. It also turns them into over-caffeinated flying machines.”
They’re still very active while this fungus erupts out of their back side, Kasson added, meaning that they’ll fly around and spores will flake off, similar to a tipped saltshaker.
How does the fungus spread?
Massospora is essentially the STD of the cicada world. Once infected with stage 1 of the disease, cicadas begin to spread the fungus to their mates.
The sexual effect on males is particularly intriguing: According to a 2018 study published in Nature, male cicadas begin to respond to other males’ mating calls using the wing-flick signals that are typically only used by females—“making them highly attractive to cicadas of both sexes,” writes author John Cooley, an entomologist at the University of Connecticut.
(Could a parasitic fungus evolve to control humans?)
Once a cicada is infected, its abdomen also fills up with spores—this is considered stage 2 of the disease. Eventually the abdomen bursts open and those spores drop into the soil where nymphs of the next generation may encounter them.
How does the fungus make cicadas so energetic?
Scientists have long been puzzled about how exactly the fungus energizes cicadas. Research has produced a leading theory—they’re essentially high as a kite.
It turns out that the fungus that infects periodical cicadas—the broods that emerge every 13 or 17 years—is filled with cathinone, a type of amphetamine and part of the family of stimulants known as speed. Cathinone occurs naturally in one type of plant, but as Gwin noted in the episode, nobody had ever recorded a fungus quite like this.
(What scientists are learning about the realm of medicinal fungi.)
“We found the same compound, the same exact compound in Massospora-infected cicadas,” Kasson said. “And they were loaded with it, which tells us that amphetamines are probably contributing to this prolonged wakefulness.”
But this chemical compound isn’t the same in every infected cicada. When Kasson studied the chalky fungal plug sticking out the back side of an annual cicada—one that emerges every year instead of periodically—he found psilocybin, the hallucinogenic compound found in magic mushrooms.
Each new cicada emergence gives scientists another opportunity to investigate exactly how and why this happens. And Kasson suspects there will be more intriguing discoveries once they do.
“It just tells us that there’s a lot there hidden below the surface,” he said. “You know, it is stranger than fiction by like an order of magnitude.
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