Some of the cicadas temporarily overtaking parts of the eastern and southern U.S. are turning into sex-crazed “zombies,” thanks to a fungus that tears off their genitals but drives them to keep mating nonetheless.
Massospora cicadina has been observed in cicadas in more than half a dozen states — both those belonging to Brood XIII, which emerges every 17 years and is concentrated in Illinois, and of Brood XIX, a 13-year group that is distributed across much of the southeast.
This is the first time these two specific broods have co-emerged since 1803 — and it’s not the only quirky (or some might say, chilling) fact about them.
The fungus is easy to spot because it replaces cicada’s backends with what looks like a “chalky white gum drop,” according to Matt Kasson, a professor of forest pathology and mycology at West Virginia University.
Kasson told NPR last month that the fungus is unique because it does “active-host transmission,” meaning that it keeps the cicada alive — and flying around — even after about a third of its body has been replaced by fungal tissue.
“This is the puppeteer — the fungus — pulling the strings on its unsuspecting host,” he said. “It's keeping the host active to attempt to mate to spread the spores.”
As part of that effort, the fungus also makes cicadas hypersexual. Typically, male cicadas make a loud mating call to attract females, who respond by flicking their wings. Infected males, in their fungus-fueled quest for world domination, will also pretend to be females to mate with other males.
Their attempts at reproduction, doomed from the start, only fuel the virus’ spread, a group of scientists at Chicago’s Field Museum of Natural History told NPR in a statement.
“Eventually, their fungal plug gets ripped open, and they fly around raining down spores, further spreading the fungus,” they wrote. “Some scientists call the cicadas at this stage 'flying salt shakers of death.' "
Periodical cicadas only live about three to four weeks once they emerge from the ground, so this year’s crop will start to dwindle later this month. The fungus, however, will live on.
“Stage I” infected cicadas pass the disease onto other adults in their same generation, according to the University of Connecticut. “Stage II” cicadas disperse spores into the soil, where they will go on to infect the next generation of cicada nymphs in either 13 or 17 years.
It’s not clear how many cicadas are infected, or whether they’re "high out of their minds"
Kasson says not to worry about the welfare of the infected cicadas, in part because of another curious side effect of the fungus.
“It turns out the fungus produces a stimulant called cathinone that likely means the cicadas don’t mind because they are possibly high out of their minds,” he wrote on X (formerly Twitter).
A study published in Fungal Ecology in 2019 reported the discovery of cathinone — a plant-associated amphetamine — in four infected cicada populations, and the hallucinogen psilocybin in some annual cicadas infected with the fungus.
The Field Museum scientists say those natural amphetamines may affect not only the cicadas but the bigger animals that prey on them, like birds. But the amount is so small that there is no risk to people or pets.
Scientists don’t know exactly how widespread Massospora is or how many of the billions of cicadas buzzing around the U.S. will be affected.
Field Museum researchers, for example, identified just seven infected cicadas out of the “hundreds” they examined on a visit to central Illinois last week.
Kasson estimates the overall incidence of infection at “maybe below 5%” — but not everywhere.
“We’ve encountered some areas where it’s as high as 20-30%,” he said, adding his team is trying to understand the reasons for such variation. “With climate change and landscape fragmentation, all these things cumulatively could tip the scales against cicadas to really impact a specific brood.”
He says his team has collected more data over the last near-decade about 17-year cicadas, so is hoping to get their hands on more infected cicadas from the 13-year population — as well as those in the part of Illinois where the two broods geographically overlap.
Kasson is also encouraging observers to alert him to any specimens they might want to contribute to his research, and tweeted this week that “the only way to truly experience periodical cicadas and their zombie cicada fungus, Massospora cicadina, is to drive out to meet them in person.” (He found 18 infected living specimens on his first day in the Chicago area.)
Anyone hoping to get up close to an infected cicada — or to avoid them at all costs — can rest assured knowing that the Massospora doesn’t pose a risk to humans.
“The fungus is also specialized to cicadas, so other animals and people can’t get infected by it,” the Field Museum scientists wrote. “They're safe to handle (but you might want to wash your hands afterward).”
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