Barklice Psocids and Book Lice: Psocoptera

Most psocids spend their time living alone. However, the larvae (LAR-vee), or young of an animal that must change form before becoming adults, of some species gather together to form colonies. Some species produce silk to make nests of various shapes and sizes. These nests may have one to many individuals living inside. Sound production in adult psocids is widely known and is thought to be a part of their courtship behavior.

Most psocids reproduce by mating, with males transferring sperm or sperm packets directly into the reproductive organs of the female. However, reproduction by parthenogenesis (PAR-thuh-no-JEH-nuh-sihs), the development of young from unfertilized eggs, is widespread. Parthenogenetic species produce only females. Eggs are laid singly or in groups. They are placed in the open, covered with silk webbing or with psocid waste material. A few species are viviparous (VAI-vih-pe-rus), or give live birth. The larvae hatch from eggs using a specialized egg-burster. The egg-burster is a bladelike or sawlike structure on the head that cuts through the eggshell as the young larva rocks back and forth inside. The larvae closely resemble the adults but lack wings and are unable to reproduce. They usually molt, or shed their exoskeletons or hard outer coverings, four or five times in four to six weeks before reaching adulthood. Some species molt only three or four times.