What are Booklice?

By Chris Williams on July 12, 2011.

Q. I have seen tiny bugs walking along the edges of old photo albums and books in our study.  My son said they were booklice and that sounds gross!Are there really booklice, and what can they do!

A. Yes indeed, booklice are real, but not at all related to head lice or body lice.  True lice are parasites and do live on humans.  Booklice, or barklice feed on microscopic molds, pollen, mosses, and lichens in nature.  Some 150 species have been identified but few classify as pests.  Most species live out doors and can be found in  places where the molds they feed on are present.  Booklice may cause the  contamination of foods and damage rare books or paper goods.  The fact that they are visible to the homeowner is also important because large numbers of any insect within a home is unsettling.  Booklice are soft bodied and resemble termites. Immature stages resemble the adults.  They are light brown to grey and may or may not have wings.  Adults reach lengths of 1mm-2mm and lay eggs about 1/3 that size.  With a life cycle taking about 1 month from egg to adult, 6 to 8 generations per year may occur under ideal conditions of temperature and humidity(80 degrees F and 65% relative humidity).  Booklice, or psocids, have biting mouth parts used for chewing their food but cannot harm humans.  As they graze on molds and mildews, the papers an starches that the molds grow on may be damaged.   Wall paper sizing, book bindings, and anywhere molds can grow will be locations booklice may be found.  Some places booklice have been observed in homes include wall voids, under floors, behind door and window trim, in closets, cupboards, outlets, in furniture, in rugs, books, paper bags and boxes, in flour, cereals(mold must be present), old trunks, straw matting/pet bedding.

Booklice will be found in damp areas with excessive humidity.  New construction with wet plaster or  damp lumber may give rise to conditions that favor mold growth, and booklice. Once the building dries out, the booklice will cease to be as noticeable.  Other notable places where booklice may be an issue are granaries, libraries, insect collections, stored foods, and in the nests of  birds or insects.  Controlling the temperature and humidity is the best way to control severe psocid infestations.  The worst case I have seen was a home that never opened the windows, ever.  In summer, condensation from  air conditioners built up on windows and other surfaces creating perfect conditions for the booklice to feed.  In winter much the same conditions were created and over time the booklice built up to incredible levels and could be seen grazing all over the home.  With the help of a heating system consultant, the homeowner was able to lower the humidity levels within the home, making life difficult for the booklice.  Pest Control Professionals at Colonial Pest Control will be able to inspect for booklice, and conditions that favor them.  Treatments can be made to limit the activity and damage caused by booklice.  Strategies for storing valuable items that may be susceptible to booklice can also be considered.   The main cause of booklice infesting a house is excessive humidity, which may also encourage a host of other pest species such as carpenter ants, beetles, silverfish, and termites.  Let us take a look and make specific recommendations regarding the booklice in your house.  



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