Here's How to Know if Your Tree Has Barklice
Three ways to identify these tiny tree-dwelling insects
Think your trees might have barklice? Never fear. First, identify these tiny insects so that you can put your worries to rest. Barklice are part of the order Psocoptera. They are commonly called barklice, a general name for the insects in the order, and they’re related to booklice (which you can often find nibbling on the binding adhesives of old books) and barkflies. The names for these insects are often used interchangeably. Common species found in North America are Cerastipsocus venosus and Archipsocus nomas; all are very small with relatively soft bodies. Some species have wings, others don’t, and many are easily mistaken for aphids.
Barklice and related species are often found on trees, but don't worry: They are known to be harmless to the trees on which they take up residence. These insects feed on the algae and lichen growing on tree bark, which has the effect of cleaning the trees of excess fungal growth and debris. The name is a bit of a misnomer, as these insects are not closely related to lice. They’re also not parasitic and not considered pests. So, how can you tell if your trees are home to barklice?
If you notice telltale wispy webbing encircling branches and trunks, you’ll know barklice have taken up residence. Some barklice, including Archipsocus nomas, which is found in the southeastern United States, spin silky webbing for protection. Because their bodies are soft, they shield themselves beneath a layer of thin silk, which they weave themselves. While the webbing can come to cover large portions of trees, it is not harmful to them, and it will disappear within a few months of its first appearance.
These insects live in large groups. They live in communities, or colonies, that are often concentrated beneath the webbing they weave, and because there are so many insects in such a high concentration, their movements are distinctive. According to the University of Florida, barklice are also sometimes called tree cattle. This is because of the way they move: When they’re disturbed, these tiny insects shift together, much like a herd of cattle, which is more noticeable than the movement of one small insect.
Barklice are easiest to spot on trees with smooth bark, like crepe myrtles, but look closely enough, and you’ll be able to identify them, especially if you notice their wispy webbing or herd-like movements. They’re also found on oaks and other hardwoods.
If you identify barklice (or, as we’re now calling them: tree cattle) on your trees this season, never fear. They’re harmless, as is their webbing. If you’re still curious, you can learn more about barklice from the Auburn University Entomology Department, the Clemson Cooperative Extension Home & Garden Information Center, or your local extension office.
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Have you noticed barklice in your trees this year? Let us know what garden insects you’re curious to learn more about.