Ophiocordyceps unilaterals - just rolls off the tongue. This tropical fungus turns ants into puppets, commanding their limbs and movements (but not touching the brain) - then kills them! The fungus grows as a "stalk" from the infected ant's body. Once the exoskeleton is penetrated, the ant convulses then "death bites" on the underside of a leaf before dying. Spores then release to infect other ants! I'm thankful it just infects ants - aren't you?

More information:

theatlantic.com/how-fungus-control-ants