Booklouse (or Psocid)

Scientific Name: Liposcelis spp. (Common household genus)

Order & Family: Order: Psocodea (formerly Psocoptera), Family: Liposcelididae

Size: Very small, typically 1 mm to 2 mm in length.

Booklouse (or Psocid)

Natural Habitat

Found indoors in high-humidity areas, damp basements, windowsills, near moldy food or paper, and inside wall voids. Outdoors found under bark and in leaf litter.

Diet & Feeding

Scavengers that feed on microscopic molds, fungi, starch (wallpaper paste, book bindings), and dead insect fragments.

Behavior Patterns

They are wingless (often) and move in quick, jerky spurts. They do not bite. They thrive in humid conditions and can reproduce rapidly if moisture levels are high.

Risks & Benefits

Risks: Generally harmless to humans and pets (no biting or disease transmission), but large numbers can indicate a mold or moisture problem in the home and can contaminate stored pantry foods. Benefits: Outdoors, they are part of the decomposition process.

Identified on: 2/25/2026