Question
"I see it is some kind of lice in texas, would it be the same in south carolina? I iave a gigantic oak the base of the trunk is 9.5' around!!! i am told its over 100 yrs old. the north side and lower branches (thats all i can see) are covered with this fine webbing, it is also on my crepe mertyl. i see those big webs with the catapillars in pecans, my neighbors trees are covered. and it didn't have the samew pattern so...
Anyway if i just wait for it to get cool, they will leave ob their own? its not damaging the tree right?

Answer
The webs on the trunk is bark lice. The webs in the pecan tree covering the leaves is Fall Webworm.

Bark Lice are more properly called Psocids (pronounced "SOSS-sids"). They are also called tree cattle because of their habit of living as a group on the bark of hardwoods, particularly oaks, and have been reported locally on citrus trees.  Large numbers of adults and nymphs are occasionally observed on tree trunks often living underneath the fine silken webbing they construct.  These insects do not attack the tree, but feed on lichens, fungi, and dead animal and plant matter.

Peer carefully under the thin webbing that is found on tree bark, and look for the one-quarter inch long adult Psocids, which are brownish-black in color. Their wings will be brown with some white markings, and appear like a roof over their body.  The younger nymphs will be smaller and look like the adults except that they are wingless. Eggs are small and are whitish in color.

Usually, the first noticeable sign of the presence of this insect is the fine silken webbing. The bark lice secrete this as a protective covering on the bark.  This silken webbing has a silvery sheen and may cover parts of the tree trunk and large limbs.  When the webbing is pulled off, it is not uncommon to see hundreds of these insects.  This webbing is not found on the twigs or leaves, and looks different than webbing produced by destructive caterpillars.

The adult female psocids lay their eggs in clusters or piles on leaves, branches, and the trunks of trees.  Upon hatching, the nymphs begin to feed on dead animal and plant matter, lichens and fungi.  They are usually gregarious, which means the adults and nymphs will remain together under the silken webbing.  When the webbing is removed, they usually all move away in a group - they  are commonly called tree cattle because of this herding habit.

Webbing barklice are found throughout Florida, and along the Gulf coast from Texas and along the Atlantic coast north to South Carolina.  They are distant relatives of the booklice, which are household pests that can consume wood and paper products.  These outside Bark lice are not a threat to either the inside environment or to Florida Yards.   Populations of these tree cattle rise and fall with the seasons - cooler weather kills off many in the winter, and as springtime temperatures rise, food sources increase, and more webbing appears.  The greatest populations are found in the fall before the onset of cooler weather.

Managing your Tree Cattle
No control measures are recommended for these insects.  If the property owner objects to the webbing of these insects, a strong blast of water from a hose will dislodge them from the tree.  But as scavengers, they perform a valuable function in consuming excess accumulations of lichens, dead bark, and other materials found on the outside of the tree.  On trees that are regularly sprayed with insecticides for other pests, psocids will rarely be seen.  If the homeowner does insist on removing these insects, a Pest Control Operator may be contracted to apply a legal insecticide.


The fall webworm, Hyphantria cunea (Drury), is most often discovered when the unsightly, light gray, silken webs on the trees in late summer and early fall are observed. Webworms enclose leaves and small branches in their nests, unlike the tent caterpillars which make a smaller nest in the crotch of branches.

This pest is native to North America and is common from Canada into Mexico. It is one of the few American insect pests that has been introduced into Europe and Asia.

Fall webworm larvae have been known to feed on over 85 species of trees in the United States. Pecan, walnut, American elm, hickory, fruit trees and some maples are preferred hosts in the most of Ohio. Persimmon and sweetgum are also readily attacked in southern Ohio while willow, cottonwood, and alder is only occasionally attacked.

Damage
This pest usually eats leaves late in the season and the nests are generally concentrated to limited areas. Because of this, little real damage is done to most trees. However, the nests can look very unsightly and multiple generations in long summers can lead to significant defoliation.
Mechanical Control - Removal of Nests - Small nests can be pruned out of small to medium trees. Monitor trees early to detect the nests when only several leaves are involved. These small nests can be easily crushed. Do not burn or torch the nests in trees as this may do additional damage to the tree.

Biological Control - Apply Bacillus thuringiensis (Bt) - The bacterial insecticide, Bt, is quite effective against fall webworms if it is applied when the larvae are small. Use formulations with UV protectants and thoroughly cover leaves next to nests. As these leaves are incorporated into the nest and eaten, the Bt will be ingested.

Chemical Control - Standard Insecticide Sprays - Most applicators attempt to "blow" the nest out of the tree with a strong jet of insecticide mix. While this generally works, more material is often used than is needed. Locate nests early and merely wet the nest and cover nearby foliage. As the larvae walk on the nest surface or incorporate new foliage, they will contact the insecticide. Second applications may be needed if additional generations occur. Because caterpillars remain in the tent, time of day is not important. Sprays can be used for control but they must be applied with sufficient pressure to penetrate the silk tent and reach the leaves within. Appropriate insecticides include Bt, diazinon, Orthene or Sevin. Read and follow label directions.