David Hughes leans back in his office in a standard-issue professorship chair as Penn State students in a plaza behind him shuffle toward classes. Between us on his desk—on either side of a paper cup of black coffee—are two trays of dead ants stuck through with pins. Some cling to leaves, others curl up around sticks, frozen in their tiny death postures like the now-fossilized humans who couldn’t escape Pompeii. All, though, have strange structures erupting out of their corpses.

This is how ordinary ants become zombies. Walking dead. Pawns of an insidious and spectacularly clever fungus.

Adapted from PLIGHT OF THE LIVING DEAD by Matt Simon. Simon is a WIRED staff writer. Penguin Books

Hughes pivots his monitor to show me a microscope photo of an infected ant’s muscle. More specifically, an ultra-thin slice of an ant muscle, so the blobs we’re seeing are cross-sections of fibers. Between these blobs, though, are tinier blobs—fungal strings that have grown through the muscle fibers, prying them apart.

Photograph slice after slice of an ant muscle like this, use AI to detect the bits of fungus and paint them green, and stack the photographs once more to make a 3-D model, and you can start to grasp the destruction the fiend has wrought. What Hughes has imaged is a muscle overwhelmed by fungus, insidious strands of green growing like grass between the fibers.

A fungus called Ophiocordyceps—to be referred to henceforth as Ophio for the sake of brevity and to cut down on misspellings—infiltrates and hijacks the ant’s muscles, but doesn’t touch its brain. “It’s basically just punching holes in the muscle,” Hughes says, pointing to said muscle. “So this is really strong atrophy, the same kind of stuff that would happen if you broke your spine.”

The fungus severs the nerves in the muscle, cutting off communication with the brain. Essentially, crippling the nervous system. And that wouldn’t seem to make a lick of sense, because up until the end, the fungus isn’t paralyzing the ant, but instead assuming precise control over its faculties.

“If I had to guess, and this is completely speculative,” Hughes says casually, “I think the fungus is forming a nervous system.”

This tale begins with the humble Ophio fungal spore living in a rain forest. Once it hits the ground, it sprouts a secondary spore that grows vertically, tipped with a bit that catches on an ant’s exoskeleton. “And these have backward-facing spines in some species,” Hughes adds. “So they just attach”—emphatic clap—“like a limpet mine. And then they literally blow a hole and eat through the cuticle at the same time.” That’s thanks to enzymes that break down the ant’s armor, plus the spore builds up pressure to equal that in the tire of a 747.

Kaboom. The fungus is in.

And what a wonderland it has found, for the ant is not just its vehicle, but an energy-rich battery. An insect is not built like us—it has an open circulatory system, so things are more or less sloshing around in the absence of a network of arteries and veins. It’s not hard, then, for the fungus to get about. As it multiplies, it soaks up more and more of its host’s nutrients.

Exploratory bits of Ophio, known as hyphae, branch out to find ever more food, growing as a network throughout the body. Fungal cells infiltrate the muscles, breaking the fibers apart. All the while, the fungal colony is talking, forming so-called anastomosis tubes—think of them like pneumatic tubes, only without the vacuum.

“This fungus has joined together in a group and they’re communicating and they’re exchanging things, that’s what anastomosis is,” Hughes says. “The question is what they’re exchanging and what they’re doing. We don’t know.” It may well be food, the exploratory bits ferrying nutrients throughout the network.