Wednesday, December 2, 2009

Horsehair Worm: Oh My God.

Speaking of parasites that feast on insects, here's one that I recently discovered:

The Horsehair Worm is a parasitic worm in the Nematomorph phylum that invades insects' bellies. It lives in water, and lays its eggs there. The eggs hatch, and wee larvae venture onto the land, where they grow little coverings that make them look yummy to certain insects. If the larva is eventually eaten by an insect, it will feast on the insect's body until it grows up. At that point, it needs to leave the host to mate and lay eggs.

One very special Horsehair Worm called Spinochordodes Tellinii affects the brain of its host (usually a cricket), causing it to hop into water, where it usually drowns. Once the cricket is in the water, S. Tellini slithers out of the cricket's body.

Here's an alarming video of the Horsehair Worm leaving its host:

Another, on land this time, with nice commentary:


  1. Cool. I have never seen a nematomorph. Do you know if the host insect continues to live after the worm exits?

  2. Aydin, I'm curious about that too! Particularly after seeing this (admittedly ridiculous) video:

    The poor insect seems to be alive as the nematamorph is leaving. But I wonder if it survives afterward?

  3. Crickets and related insects breath through small holes (possibly called spicules? I don't remember) all along their legs and maybe their abdomens. Even if the wound through which the worm exits is not fatal to the cricket, it will get waterlogged and drown pretty quickly.

    On the bright side, the crickets that hairworms bring to streams are a food source for salmonid fish...

  4. Spricales! They're called spircales, sorry.

  5. Yeah, I think you're right, Anon, that it's a dismal situation for the infected insect.

    Whoa, I just read this: "If grasshoppers and crickets are preyed upon by fish and frogs, the gordian worm can escape this predation by wriggling out of the mouth, nose or gills of the predator once it has emerged from a host that has been eaten." I would hate to have a nematomorph slither out of *my* nostril. Bleh.

  6. Hey Julia,
    I recently heard a radiolab podcast that explored paracites - I thought you might enjoy it
    I love this new progression in your work!
    see you Saturday,

  7. Oh boy--thanks Nina! I can't wait to check it out. Yes, looking forward to catching up on Saturday!