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.
Last updated: December 17, 2017