Bark Lice nymphs by Bernard DUPONT/CC BY
Bark Lice nymphs by Bernard DUPONT/CC BY

What is that mysterious webbing on the trunks of your oak trees?  Fortunately, the webbing is not caused by webworms or caterpillars, but by a beneficial insect commonly known as Barklice.   As scavengers, they perform a valuable function in consuming excess accumulations of fungi, algae, dead bark and other materials that occur on tree trunks & limbs.  They don't eat the leaves or bark of the tree or damage the tree in any way.

Except for their very small size, Barklice do not even look like lice.  They are insects about 1/8 inch long, brownish-colored, and resembling aphids.  They live together underneath the protective layers of their silken webbing, which normally appears in late summer (July & August).

The silk webbing can completely envelop the trunk and large branches. Their webbing and Barklice themselves, are harmless and will disappear during the onset fall weather. Their web provides protection from predators while allowing the insects to feed.

No control measures are recommended for these insects since Barklice are providing a beneficial service by helping Mother Nature to keep the tree bark clean and tidy!