Booklouse (Liposcelis corrodens). Photo: Kansas Department of Agriculture ,

Updated: March 1, 2023
  • Booklice (psocids) are tiny insects. They are 1 to 2 millimeters long, and range in color from almost colorless, to gray or light brown.
  • Booklice prefer damp, warm, undisturbed situations. They become most numerous in houses during spring and summer.
  • Booklice mostly feed on mold spores, but may also feed on starchy materials. They usually cause no damage.
  • The most effective way to control book lice is to reduce moisture and/or humidity.
booklice nymph

Booklice adult and nymph. Photo: John Davidson, University of Maryland

Rev. 2020