http://en.wikipedia.org/wiki/CordycepsCordyceps are endoparasitoid fungi that infect insects and arthropods, and some are capable of, through chemicals that alter the brain, force an insect bite onto a leaf hanging upside down with all its might until death. That makes its spores spread, and the cycle repeats.
We had a topic on this sometime back.
Anywho, this stuff gives me the shivers when I see it.

Especially that picture.
So yeah, talk about this fungus from the depths of hell.