A psocid (Order Psocoptera) is a common insect that can be found both indoors and outdoors. Psocids that live outdoors are known as “bark lice” because they are commonly found on or under the bark of trees. Indoor psocids are called “booklice” because they are often found feeding on the damp pages of old books. Read on for more information about psocids and how to get rid of them. 

What are psocids?

Psocids range in size from 1/25th to 1/13th of an inch. They are cream-colored to pale white. The psocids, or “bark lice”, that live outside can be found on trees, but also on rocks, fence posts, and picnic tables. 

“Book lice” found indoors are extremely tiny and difficult to see. They are wingless and are common in moist or damp areas. They are often found near old books stored in damp conditions, such as in a basement. Both types of psocids feed primarily on microscopic molds, and they need to live in moist environments where such molds can grow. They can be found in most buildings but are rarely seen in homes as pests. When outdoors, they are rarely considered a problem.

Booklice vs. head lice vs. fleas

Due to their tiny size, psocids like booklice and bark lice, headlice, and fleas can all be confused for one another at first glance. A pest control expert can help you identify the insect you’re dealing with, but some obvious features to look for include:

  • Habitat: Booklice are found both indoors and outdoors in moist areas. Headlice are found in the hair and scalp of humans. Fleas live outdoors in grass, wooded areas, leaf litter. Also attach to warm-blooded animals like humans, pets and more. 

  • Bite: Booklice don't bite. Headlice bite and can cause itching and redness in humans. Fleas also bite, with their bites appearing in itchy, red clusters or a small, discolored bump with a ring around it.

  • Diet: Booklice eat microscopic molds. Headlice eat human blood. Fleas feed on the blood of their hosts, usually mammals and birds.

How do booklice get in your house?

Psocids may be present in a new house that has either just been built or has been left vacant for a longer period of time. They get inside through cracks and crevices in the wall or travel inside on molding or moist firewood. Booklice might also hitch a ride on books that you picked up at a thrift store or a garage sale.

Once inside, they’ll seek out a moist, humid area where they can thrive and reproduce, like basements, bathrooms, and other small, tight spaces. 

How long do psocids live for?

The total lifespan of a psocid depends on the temperature and humidity of its environment. They go through egg, nymph, and adult stages, molting three or four times along the way. The time it takes to go from egg to adulthood can range anywhere from one month to three months or slightly longer.

Depending on the temperature, females can lay about 60 eggs over the summer and fewer over the winter.

Do psocids bite?

Unlike true lice, neither bark lice nor booklice bite, and psocids are not harmful to humans and pets. They have long, “chisel-like” upper jaws that may look threatening, but they use their mouthparts exclusively to feed on organic material, not to bite. 

How to help get rid of a booklice infestation in your home

Since they are primarily attracted to moisture, the best way to eliminate booklice in your home is to take care of any moisture issues. Use fans in bathrooms and dehumidifiers in basements to dry out any problem areas. If moisture isn’t taken care of, the use of insecticides and other store-bought products to get rid of psocids won’t be effective. 

Prevent an infestation by thoroughly checking any books and other second-hand products you bring into your home. Store books and paper off the floor in a dry area to prevent mold growth. Lastly, seal up any cracks and crevices in doors and windows to stop all pests from making their way inside.

Need advice on psocid control? We can help with pest control strategies that are tailored to your needs.