A 17-Year Wait for a Fungal Ambush
In the forests of the Eastern United States, a specialized fungus called Massospora cicadina lies in wait. It is a predator, synchronized to the 13- and 17-year life cycles of its host: the periodical cicada (Magicicada spp.). When cicada nymphs tunnel toward the soil surface after more than a decade underground, they encounter the fungus's resting spores. This initial contact triggers the infection.
As the infected nymph molts into an adult, the fungus grows within, consuming the insect's internal tissues. The process culminates in the complete destruction and replacement of the cicada's abdomen and genitals with a chalky white plug of fungal spores. Despite this transformation, losing up to a third of its body—the cicada does not die. It continues to fly, call for mates, and interact with other cicadas, now acting as a vector for the pathogen. Researchers refer to these infected insects as "flying saltshakers of death" because their movements effectively dust other cicadas with spores.
Chemical Manipulation
The fungus's ability to keep its mutilated host active is because of chemical warfare. Research led by West Virginia University revealed that Massospora cicadina produces a potent psychoactive amphetamine called cathinone. This is the same stimulant found in the khat plant (Catha edulis) and is chemically related to synthetic cathinones known as "bath salts." The cathinone appears to induce a hypersexual state, compelling the infected cicadas to mate relentlessly and spread the fungal spores.
This behavior includes complex behaviors; infected male cicadas begin to mimic the wing-flick signals typically used by females to signal receptiveness to mating. This behavioral change lures healthy males who, attempting to copulate with the infected male, become contaminated with fungal spores. This way of using a living host for transmission is known as active host transmission (AHT) and is rare among fungal pathogens, which more commonly disperse spores from a dead host.
The infection unfolds in two stages. Stage I produces spores, called conidia, that spread rapidly among the adult cicada population during an emergence. Cicadas that contract the fungus from another adult enter Stage II. In this phase, the fungus creates thick-walled resting spores. These durable spores are designed to fall to the forest floor and remain dormant in the soil, ensuring the fungus will be present to infect the next generation of cicadas when they emerge 13 or 17 years later.