'Zombie' ants are dying in a disturbing way, and scientists are puzzled

Morgan Hines

The zombies on 'The Walking Dead' may be fictional, but "zombie ants" are very real.

A fungus is turning carpenter ants into unwitting hosts until they die and decompose, according to a new study from Pennsylvania State University researchers.

"The term 'zombie ant' is a reference to the fact that the ant essentially becomes a vehicle by which the fungus can grow and reproduce," Colleen A. Mangold, lead author on the study, told USA TODAY.

The fungus, 'Ophiocordyceps unilateralis sensu lato,' infects ants' muscles rather than their brains, causing them to hyper-contract. The fungus is not harmful to humans.

The article, published in the peer-reviewed Journal of Experimental Biology, said that that results in a death grip.

Ants infected by the fungus climb to elevated places and bite onto vegetation, becoming permanently affixed, the team found.

That's because the fungus triggers a permanent muscle contraction when an ant bites onto a leaf vine or twig, Mangold said, though scientists don't yet know how.

United Airlines passengers: Discover their trans-Atlantic flight is crawling with ants

"The biting behavior is thought to benefit the fungus in that it essentially ensures that the ant is secured in a location where the climate is optimal for fungal growth," said Mangold.

This means that after the ant dies, the fungus can continue to grow and then emerge from the ant's body, sometimes in the form of fungal stalks.

The continued growth releasing infectious spores which can spread the fungus to other hosts.

An ant walks across a leaf avoiding droplets of rain water.
An ant walks across a leaf avoiding droplets of rain water.

The team studied the fungus and its effects on ants by using a strain found in South Carolina.

The ants infected in the lab started to demonstrate stereotypical changes in behavior after a period of between 15 and 30 days.

Mangold said that there is a continuous low infection rate among ant colonies infected by the fungus.

Follow Morgan Hines on Twitter: @MorganEmHines.

This article originally appeared on USA TODAY: Bugs with 'zombie-ant' fungus bite with a literal death grip