Bark Lice Infecting Trees

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Cary Sims
Cary Sims is the County Extension Agent for agriculture and natural resources for Angelina County. His email address is cw-sims@tamu.edu Educational programs of the Texas AgriLife Extension Service are open to all people without regard to race, color, sex, disability, religion, age, or national origin.

Recently, concerned homeowners have called about their tree’s trunks and limbs being covered in a webbing. The leaves are fine and not being consumed by the normal caterpillar culprits. But what is this webbing and will it hurt the trees?

The webbing is from a seldom seen insect commonly called bark lice. These small insects called barklice or psocids are completely harmless to the tree.

The insects are around during most years but are only noticed when population levels are high, and their webbing becomes more apparent. Because barklice cause no damage to the trees, no control is recommended.

The webbing, which can extend from the trunk into the foliage, is quite thin and fragile and is expected to disappear in a few weeks. Heavy infestations of bark lice seem to be associated with relatively long periods of high humidity.

Homeowners often express concern when they see the trunk and most limbs of their trees encased in a giant silken web. Under the webbing, you’ll find bark lice as a small, soft-bodied insect with long antennae. To those who are armchair entomologists, they may resemble aphids.

To be clear, even though these insects are called bark lice, they are not lice. They are not parasitic on anything, and they are not pests of humans or animals.

The adults are about 1/8th-inch long and possess two pairs of membranous wings that are held roof-like over the body when at rest. Bark lice have simple metamorphosis and go through three stages — egg, nymph, and adult. The nymphs resemble adults except they are smaller and lack wings. Barklice have chewing mouthparts and are considered a beneficial insect since they feed on fungi, spores, pollen, lichens, and other debris on the surface of a tree’s bark. In effect, they will clean your tree trunk and limbs of any debris.

Most importantly, they do not harm the trees they infest. The bark lice that produce the webbing on trees in Texas belong to the insect order Psocoptera and have the scientific name Archipsocus nomas. They can be found in all the southern states from Florida to Texas. Water oak (the semi-evergreen oak of the south) seems to be the most common tree on which the webbing is found.

They are not known to produce webbing on pine trees.

If you just absolutely feel the need to remove the webbing and get rid of these insects, use a hose-end sprayer with an insecticidal soap to wash away the webbing and eliminate the bark lice.


Cary Sims is the County Extension Agent for agriculture and natural resources for Angelina County. His email address is cw-sims@tamu.edu. The members of Texas A&M AgriLife will provide equal opportunities in programs and activities, education, and employment to all persons regardless of race, color, sex, religion, national origin, age, disability, genetic information, veteran status, sexual orientation or gender identity and will strive to achieve full and equal employment opportunity throughout Texas A&M AgriLife

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