Zombies are cool, right?
Basically, the fungus controls the behavior of the infected ant, causing it to climb to an ideal spot and clamp down with its mandibles… and die. Thus allowing the fungus to grow a fruiting body and spread its spores. Infected ants are sometimes called “zombie ants”, not because they rise from the dead, but because of the mind-controlling behavior of the parasite. I’ll let Sir David Attenborough tell you more:
And if you can handle really terrible narration, you can’t miss out on snail zombies:
If you need some fun lunch-time reading, here is an article by Carl Zimmer on “How to control an army of zombies“.