Book louse (or Booklouse, plural: Booklice)
Scientific Name: Liposcelis spp. (Commonly Liposcelis bostrychophila)
Order & Family: Order: Psocodea (formerly Psocoptera), Family: Liposcelididae
Size: Very small, typically 1 mm to 2 mm in length.
Natural Habitat
Found indoors in damp, warm, and undisturbed areas. Common locations include bookshelves, window sills, behind wallpaper, in cupboards stored with dry goods, and in new construction where plaster is still drying.
Diet & Feeding
They feed on microscopic mold and fungi found on paper, glues, book bindings, and damp household materials. They also consume starch-based materials like grain, flour, and cereals.
Behavior Patterns
They are flightless, fast-moving insects that prefer high humidity. They do not bite but reproduce rapidly via parthenogenesis (asexual reproduction) in favorable warm and humid conditions. They are often seen scurrying across paper or walls.
Risks & Benefits
Risks: Generally harmless to humans and pets (no biting or disease transmission), but can contaminate stored food products and, in large numbers, cause psychological distress or allergic reactions in sensitive individuals. Benefits: None significant in a household setting, though they help break down detritus in nature.
Identified on: 2/19/2026