Horsehair Worms

Last week when it was a bit milder and we had some rain, I spotted this piece of thread on our sidewalk.  At least I thought it was a piece of thread – except it was moving like a snake – even rearing its head up off the ground.

Odd.  I’d never seen any snake quite so small, so I of course started researching.  The closest I found were called thread snakes, but all the photos of them on the net were so much larger.  I emailed this photo to the  KY Dept. of Fish & Wildlife Info Center, which forwarded my inquiry to Herpetologist John M.

John kindly filled me in on these weird critters – not snakes at all but a parasite called a horsehair worm. These worms begin life in the bodies of crickets, grasshoppers, beetles, roaches and similar insects.  When they reach the adult stage of development they break out of the host body to live in damp soil or shallow water.  The adult worms reproduce, laying eggs that are in turn eaten by the cricket or beetle, thus repeating the cycle.  The amazing thing is that the worm is able to force the host insect to go to water before it dies, so that the adult worm has the suitable habitat to live and reproduce.

Apparently they got their name because the folks who first encountered them thought they were horse hairs that fell into the water and turned into snakes or worms.  Really?  Were our ancestors really that dense?

When I saw these worms in our yard I didn’t know about the host insect, but supposedly when you see one there’s probably a dead cricket or grasshopper in the water nearby.  I’ll be on the lookout for this strange little drama unfolding in my yard after the next warm rain…

Oh, and they are completely harmless to humans and animals – good thing, since we have both on our property.

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