Booklouse (or Barklouse)

Scientific Name: Liposcelis spp. (Family Liposcelididae often encountered indoors)

Order & Family: Order: Psocodea (formerly Psocoptera); Family: Liposcelididae (common indoor varieties)

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

Booklouse (or Barklouse)

Natural Habitat

Found in damp, humid environments indoors such as basements, bathrooms, or near windows; often resides in old books, cardboard boxes, or areas with microscopic mold growth.

Diet & Feeding

Feeds on microscopic mold, fungi, starch, glue (from book bindings), and dead insect fragments.

Behavior Patterns

They are wingless (mostly) and run quickly when disturbed; they thrive in high moisture which promotes the mold growth they eat; they do not bite.

Risks & Benefits

Generally harmless to humans and pets as they do not bite or spread disease; primarily a nuisance pest indicating high humidity or potential mold issues; in large numbers, they can damage starchy materials or contaminate stored grains.

Identified on: 3/2/2026