Yes, that's right: ant zombies.
In the South American rainforest, ants have a mortal enemy: the parasitic fungi in the Ophiocordyceps (also known as Cordyceps) genus. These fungi infect ants and other insects, forcing them to do its fungal bidding. For example, a spore-infected zombie ant will climb to a perfectly selected spot in the canopy where it will die. At this point a fungus stalk blooms out of the ant's head; once fully grown the fungus will burst open spreading spores over the area and infecting other ants. Each zombie-inducing fungus species is specifically linked to one ant or other insect species.
http://www.scientificamerican.com/article.cfm?id=fungus-makes-zombie-ants
-Sharon