CHICAGO (WGN) — A sexually transmitted disease that is said to turn cicadas into “zombies” and causes their genitals to fall off has been detected in southern parts of Illinois and is spreading throughout the Midwest.

The fungal infection, called Massospora cicadina, targets only the 13- and 17-year periodical cicadas. This year’s “cicada-geddon” is brought to us by one each of Brood XIII, which is primarily in Illinois, Iowa and Wisconsin, and Brood XIX, which extends south and east from there.

Massospora cicadina has already infected cicadas in Champaign, Illinois, and is expected to migrate north to the Chicago area, according to Jim Louderman, a collection’s assistant at Chicago’s Field Museum of Natural History. Experts in Missouri say the fungus has also started impacting cicadas there.

Birds that eat the infected cicadas may also experience hallucinatory effects.

The white fungus takes over male cicadas and causes the gonads to be torn from the body. The chalky spores that are released by the fungus are spread to other nearby cicadas, infecting more and more.

The fungus also takes over the way the cicadas behave. Even though their reproductive parts have been replaced by a fungus, they are driven to mate with as many other cicadas as possible, Dr. Matt Kasson, an associate professor of mycology and forest pathology at West Virginia University, explained to CNN.

Infected males also flick their wings in an attractive way, luring in more victims.

“It turns infected cicadas into ‘zombie insects’ that disperse more fungus by causing males infected with Stage I [of emergence] to produce wing-flick signals as if they were females– making them highly attractive to cicadas of both sexes,” the University of Connecticut explains.

By fervently mating with healthy cicadas, the sickened insects spread the fungus far and wide. And with trillions – potentially even hundreds of trillions – of cicadas emerging this year, the fungus has a lot of insects to prey on.

For those whose neighborhoods are still plagued by swarming cicadas, perhaps some of them zombies, relief is on the way. The cicadas tend to disappear a few weeks after they appear, once they’ve successfully laid eggs. That means most parts of the country will be quiet, rid of the roaring cicada song, by the end of the month. Some cicadas could linger into early July.