The fluke larva then makes it's way to the ant's brain after a time, and controls the ant to grasp onto the tip of a drooping blade of grass and stay there.
I saw a program that featured parasitic fungi that do similar things. One which infects ants causes the infected ant to travel upwind of its colony, climb to the top of a blade of grass and clasp onto it and wait for death. After it dies the fungus' spore structures erupt from the ant and send their spores blowing in the wind toward the colony to infect more ants. According to the show worker ants can recognise an infected ant in the early stages and will attack it and carry it far from the colony. Don't recall if they figured out to carry it down wind or not.
The other fungus attacks flies, and causes them to do basicly the same thing. Land on something tall and exposed to the wind, and wait to die. The spores wind up being cast to the wind to infect more flies, but it is left a little more to chance than with the ants.
Back to the horsehair worms though (sort of), a few years ago I was diving in Lake Superior and saw what at first I thought was a horsehair worm but when I looked at it closely, I saw that the ends were not tapered. Not only were they blunt, they were flat. Imagine a soup can stretched out. When I saw this I thought maybe it was just a chunk of thick monofilament, but when I put it into the water column, it did undulate and swim the way a horsehair worm would. I looked around on the rest of the dive and actually saw several more of these and they were definitely alive. Anyone know what they might have been, just a different species of horsehair worm maybe? I was diving on a wreck at the time and if my memory is working right, I saw these around the wooden parts of the wreck. Don't know if that was a coincidence or not. The horsehair worms I am most familiar with are the ones that infect crickets, darker in color and definitely tapered at both ends. The ones in Lake Superior were kind of gray in color.