Hairworms have a perpetual challenge: They infect landlubbing insects like crickets, but the parasites must make their way to an aquatic habitat in order to reproduce.
Researchers at France's Centre National de la Recherche Scientifique figured out how they accomplish this feat. Hairworms produce mind-controlling chemicals that cause their cricket host to move toward light. Because water bodies reflect moonlight, this often sends crickets toward lakes and streams.
The crickets jump in and drown, and the hairworms emerge, ready to find their next victim.