Booklice and Psocids



Booklice (Tony Willis, Wikimedia Commons)


Booklice (David Sheltar, Ohio State University,


Barklice (Wikimedia Commons)


  • minute: 1/25 - 1/13 inch long
  • booklice found outdoors may be larger, up to 1/4 inch
  • very common in pest monitors; look like small specks (use hand lens to identify)
  • may have wings or not
  • other species of psocids are called barklice

Nesting Habits

  • prefer warm, humid or damp places
  • can be found around damp books, around leaking/sweating pipes, in voids, in cardboard boxes or anywhere where mold growth can be supported
  • barklice live outdoors on/under bark, grass, leaves, damp wood, etc.


  • mold spores
  • may feed on fungal spores on stored food products


  • nuisance pest indoors
  • indicator of moisture issues

IPM Recommendations

  • Reduce relative humidity within trouble areas.
  • Vacuum.
  • Remove leaf litter from around the exterior of structures.
  • Store food items in pest-proof containers.

Additional Resources:

Booklice and Their Relatives fact sheet

IPM for Silverfish, Firebrats, and Booklice: Integrated Pest Management in Sensitive Environments (University of Nebraska-Lincoln Extension)