Have you ever seen tiny, lightly-colored insects crawling around your home or garden? If so, you may have been seeing psocids. These soft-bodied pests rarely grow larger than three-sixteenths of an inch long, making it difficult to spot a few of these pests outdoors. However, some of the psocid species are 1/10th this size (size ranges from 0.04 inch to 0.4 inch or 1/25” – 3/16”), just barely visible without magnification. With the smaller species there can be hundreds or even thousands of them, making the group of them more noticeable than an individual psocid would be.


What Are Psocids?

Because of their size, psocids are often confused for a variety of other pests, including springtails, fleas, and lice. This confusion has led many to refer to psocids as “barklice” and “booklice,” depending on where these pests are found. The term “barklice” refers to the species of psocids that live outside. Like this colloquial term suggests, these species primarily live on and underneath tree bark, as well as within leaf piles, grass, and damp logs. These species have two pairs of wings, which they may use to travel from point to point. However, because these pests are not strong fliers, these flight patterns can closely resemble hopping, which can lead homeowners to confuse barklice with fleas and other pests.

The term “booklice,” on the other hand, refers to the species of psocids that primarily inhabit the indoors. These species are wingless and tend to infest moist areas of a home, like bathrooms and basements, where molds and fungi are more likely to grow. As the term “booklice” suggests, these pests also feed on starchy materials, like the glue found on book bindings. Homes located in particularly humid regions may also see these pests feeding on microscopic mold growth between book pages, though booklice rarely cause damage to the books themselves.

Do Psocids Bite?

Unlike true lice, which may bite their human host several times a day to get a full blood meal, psocids do not bite. Their anatomy may suggest otherwise, however; as entomologists from Texas A&M University note, psocids have broad heads and a prominent clypeus, or area located near the mouthparts, that may give the impression that psocids can inflict bites on humans. But as specialists from North Carolina State University confirm, psocids “do not bite or transmit disease.”

Instead, these pests use this anatomy, as well as their mandibles, to feed on small particles of organic material. As the Encyclopedia Britannica points out, psocids have a long, “chisel-like” upper jaw that ensures these pests are adept at chewing material. While they primarily feed on fungi and other organic matter, some species of booklice can be found in packages of flour, cereal, or other grains. In fact, according to faculty from the UC Division of Agriculture and Natural Resources, “you've probably unknowingly eaten [psocids]--or parts of them--in your pancakes, your oatmeal or maybe even your chocolate birthday cake.” Though eating booklice is not believed to pose harm to humans, the article also mentions that any homeowner worried about consuming food infested with booklice can bake the contents in their oven at 120 degrees Fahrenheit for 30 minutes, and then store the contents in an airtight container. Though there may be a few dead booklice living within the grains, baking the food can help kill any booklice still living on the material.

Preventing Psocids

Other than being a slight nuisance, it’s not believed that psocids can cause damage to the inside or outside of a home. Still, you may not want hundreds of tiny pests living among your family. Because these pests are drawn toward moisture, homes located in humid regions of the country may be more susceptible to a psocid infestation.

To help prevent large numbers of psocids from infesting your home, researchers from the Department of Entomology at Iowa State University ensure that insecticides are not needed to help control psocids found indoors. Instead, it’s best to remove any infested items, like food products, , from your home and address any high levels of humidity that could be attracting these pests. As researchers at the University of Minnesota notes, psocids cannot survive when the humidity falls below 45 to 50 percent, so using a dehumidifier or fan in damp rooms can help deter these pests. Likewise, it can be helpful to keep all books, papers, and cardboard boxes off the floor to limit their exposure to collected moisture.

But what about barklice? Psocids are a natural occurrence outdoors; these pests have even been considered beneficial to the trees they infest because of their tendency to feed on mold and fungi. The University of Minnesota also recommends you “check rooflines for poor attic ventilation, trees overgrowing the roof, and leaf litter in the eaves,” and contact professionals to help correct these issues.

Considering psocids are a common outdoor pest, it’s important for homeowners to know more about what these pests eat, where they live, and what attractants can cause a psocid infestation inside a home. Visit our blog to learn more about psocids and other unique pests.

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