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 damp, humid environments like basements, libraries, or bathrooms; also found in stored food products (grains, cereals) and old books or paper

Diet & Feeding

Feeds on microscopic molds, fungi, starch, book bindings, glue, and occasionally stored grains

Behavior Patterns

They do not fly (wingless species are common indoors); they run quickly when disturbed; often found swarming on damp surfaces where mold grows; parthenogenetic reproduction allow populations to grow quickly

Risks & Benefits

Risks: Nuisance pest; can contaminate food; indicators of high humidity/mold issues; can cause allergic reactions in sensitive individuals. Benefits: None significant to humans, though they play a minor role as scavengers in nature

Identified on: 2/15/2026