The tropical fungus Ophiocordyceps infects ants' central nervous systems. Once it has been in an insect's body for nine days, it has complete control over the host's movements. According to National Geographic, it forces the ant to climb trees, then convulse and fall into the cool, moist soil below, where fungi thrive. Once there, the fungus waits until exactly solar noon to force the ant to bite a leaf and wait for death.