Psocids
Summary: Psocids are very small insects measuring 1 to 4 mm. They are more commonly called booklice and their presence may be a sign of a mold problem in your home.
The oldest psocid fossil was found in Kansas and was thought to have lived about 290 million years ago, or 284 million years before man made his first appearance. So, no matter what you do, you cannot expect to totally defeat the psocid.
The psocid (pronounced so-sid) is a tiny insect measuring 1 to 4 millimeter in length. Its most outstanding feature is its long schnozola, or as it is better known, beak. Psocids are almost always gray, clear, or white and have long antennae. Some species have four wings, while others are wingless. Just when you thought you knew of all the flying pests, you learn about another one you want to avoid.
![]() booklice |
If you imagine a small critter, you probably think of lice, right? Then it is quite appropriate that some species of psocids are called barklice. This species clings to bark on trees and logs, and occasionally camps out under rocks.
The psocid feasts on pollen, decaying plants, and fungi, and even flakes of dead skin from humans and other animals. At least some something is profiting off of your sunburn and peeling skin from your vacation in Cancun. The psocid usually does not eat human food, but it will if mold is growing on it. Yet another reason to throw out the three-weeks-past-expiration-date cheese sitting in your fridge.
The smaller species of psocid, booklice, are commonly found around paper and books. They enjoy munching on the glue that binds books together. This psocid cannot hurt humans or animals, but they can become a problem because they tend to congregate in large numbers. In fact, they may gather by the hundreds or even thousands.
Besides paper products, booklice also feed on mold and fungi, especially in warm, moist places. So, if you discover booklice creeping around your house, it may be a sign that you have mold growing in your basement, bathrooms, or any other location with excessive moisture.
![]() barklice |
Psocids can also become a problem during the summer months because they thrive in warm temperatures. In the winter, the mature psocids will die, but their eggs will hatch in the spring. As temperatures turn colder, be sure the firewood you bring inside is nice and dry. Moist firewood is sure to have psocid infestations.
Getting rid of mildew or mold problems will greatly increase your chance of killing psocids. If you have an infestation, you can’t procrastinate about disinfecting your bathroom any longer. Insect sprays are deadly to psocids, so try using these on your new visitors. (Follow label instructions.) If barklice are living on your trees, a strong hose should do the trick to wash them away.


