What's with all this webbing on my oak tree?

Lately, I have been noticing a lot of webbing on the live oak trees in the New Orleans area. I have also received a lot of telephone calls with concerns of why there is thick webbing covering the bark of old oak trees. This mysterious webbing is placed on the tree by bark lice (Archipsocus nomas), and aids in reducing the amount of predation on its population. Bark lice are often found under the webbing in clusters, and when the cluster is disturbed the cluster of bark lice scatter. These small insects were referred to as tree cattle in the older literature because of this herding behavior. The adult bark lice is brownish-black and approximately ¼ inch long, and the immature stage, or nymphs, are similar in appearance except they do not have wings. Bark lice feed on fungi, algae, dead animals and plants, and lichen found on the tree. Bark lice are considered not harmful to the tree, but rather somewhat beneficial. Although the webbing may be unsightly on your tree, the webbing appears from July and is more extensive in
as population numbers grow October. As a positive note, these insects decorate your trees with a natural Halloween decoration. If left undisturbed the bark lice will begin to eat their webbing as the population declines by the end of the year. Bark lice do not warrant any chemical control, and should not be sprayed.