Booklouse (or Barklouse)

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.

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

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.

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.