The fungus Massospora cicadina preys on Magicicadas cicadas. This is particularly interesting because the fungus is able to prey upon them in spite of their long 17 year life cycle (apparently fungi are not phased by prime numbers).
When the fungus destroys the abdomen of male cicadas, they begin behaving like female cicadas.
A photo by Roy Troutman from Brood XIV (2008):
Two photos by Dan Mozgai from Brood II (2013):
Magicicada fungus (massospora cicadina)