Carl Zimmer in his excellent blog, The Loom:
When I first learned about the fungus Cordyceps, I refused to believe.
I was working on a book about the glories of parasites, so I was already in the parasitic tank, you could say. But when I read about how Cordyceps infects its insect hosts, I thought, this simply cannot be. The spores penetrate an insect’s exoskeleton and then work their way into its body, where fungus then starts to grow. Meanwhile, the insect wanders up a plant and clamps down, whereupon Cordyceps grows a long stalk that sprouts of the dead host’s body. It can then shower down spores on unfortunate insects below.
I mean, really.
Yet this video from David Attenborough faithfully depicts the actual biology of this flesh-and-blood fungus. I also discovered that Cordyceps is not the only species that drives insect hosts upward. You don’t even have to visit a remote jungle to see one. Here in the United States, houseflies sometimes end up stuck to screen doors thanks to a fungus called Entomophthora muscae. And the lancet fluke Dicrocoelium dendriticum uses the same strategy to get into cows.
Call me naive, but I assumed that creatures as freakish and wonderful as Cordyceps and company would attract enormous amounts of scientific attention. Yet I was frustrated to discover that hardly any research has been carried out on their powers of manipulation. That’s a shame, because you cannot assume that these parasites are indeed manipulating their hosts. It’s possible, but it’s just a hypothesis that requires testing.