Fast Facts About Horse Hair Worms

The horse hair worm, or Gordian worm, is a very long, thin worm similar to a nematode. Gordius robustus gets its common names from the appearance of the worms in water, where it resembles a mass of hairs dropped from a horse's mane. While breeding, the worms knot themselves into a loose ball resembling the Gordian knot of mythology. The worm cannot harm a human, nor is it a pest to gardens. It is a beneficial insect as it kills crickets, grasshoppers and other herbivorous insects that feed on crops. The horse hair worm has four life stages.

Egg
- Adult worms lay sticky, gelatinous strands of eggs in standing water. The strands can be up to 24 inches long and may be found in ponds, slow moving streams or livestock troughs. It takes about a month for the eggs to hatch.
Pre-Parasitic Larvae
- Crickets are a common host of horse hair worms.
  
  After the eggs hatch, the microscopic larvae swim about in the water, waiting to be consumed by an insect drinking from the water. Once eaten, or if the water dries up, the larvae encysts itself and begins to enter the next stage. Encysted larvae may also be consumed by insects after the water dries up.
Parasitic Larvae
- Grasshoppers are another host insect to the worms.
  
  The parasitic larvae leaves the cyst inside the host's body and will spend the next three months feeding on lymph, the insect equivalent to blood. As a result of the feeding, the insect is highly unlikely to breed, and will become ill.
Adult
- When the larvae has reached full growth, the insect will become intolerably thirsty, and as it begins to drink, the worm will be prompted to emerge. Adult worms must emerge into water, where they are pale or white at first, and darken to brown or black within a few days. Emergence of the adult worms kills the host. Adult worms do not breed, but burrow into the mud for winter, then emerge in the spring to mate, lay eggs and die.