Adult Bark Lice are approximately 6 mm long; with a brownish-black body with white edges and stripes on wings. Their wings are held roof-like over their body. Nymphs look similar to adults but are wingless. Large populations may produce a great amount of silk webbing on a tree, but no damage is done. Insects feed on fungi, spores, pollen, lichen, and other debris on a tree's bark.
Signs of infestation include: Small portions or entire tree trunk covered with a fine silk webbing. Dark area on trunk or branch comprised of several hundred psocids or bark lice.

Photo Courtesy of Texas Cooperative Extension.