Horsehair worms are the aquatic adult phase of little-known invertebrate animals. The immature stages are parasites in the bodies of grasshoppers, crickets, cockroaches, and some beetles. When mature, they leave the host to lay eggs. These interesting creatures are not parasites of humans, livestock, or pets, and pose no public health threat. The adult “worms” mate in water and females lay long gelatinous strings of eggs. After the eggs hatch, scientists believe that each larva forms a protective covering or cyst. If the cyst is eaten by a suitable insect, the protective covering dissolves and the released larva bores through the gut wall and into the body cavity of the host. There, it digests and absorbs the surrounding tissue. When mature, it leaves the host insect to start the process again. Emergence from the host occurs only when the host is near water. Occasionally, they are found after a cricket or cockroach is killed by someone crushing the insect, at which time the worm begins to wiggle out of the insect’s body.

Horsehair worms have also been seen in the caves of Carlsbad Caverns National Park and in streams in the Guadalupe Mountains. They are fascinating, but rarely encountered.

We can guess—fairly accurately—that the park provides habitat for numerous other strange invertebrate animals that are yet to be studied.