While searching the internet for cool science stuff (something I do more often then you would think), I remembered one of my favorite segments of Planet Earth. Little known fact, I love the series and have seen most episodes many times. Anyways, this segment is about a fungus called Cordyceps. Remember yet? Well this fungus is parasitic among insects and has very unusual consequences. One group of insects that is majorly affected by this fungus is ants. Cool fact: infected ants that are found by other members of the colony are carried away to prevent spreading of the fungus spores.
Once ingested, the fungus causes insects to become delirious and disoriented, and some species of Cordyceps can even cause the insect to climb a plant and attach to a branch. The rest of the process...well its better if you see it yourself.