Description & Habits
Barklice are members of the order Psocoptera, and there are over 300 species in 26 families in the United States and Canada. They are small and, with few exceptions, inconspicuous insects. They are soft-bodied, and usually less than ¼-inch in length, with long antennae and two pairs of wings carried folded over their backs. Although these insects resemble aphids and are called “lice,” they are not pests or parasites of either plants or animals nor are they true lice. Most barklice live outdoors in a variety of habitats and are commonly found on trees. Unlike caterpillars, Barklice undergo simple metamorphosis (meaning that the young resemble the adults) and pass through six nymphal stages (which are also called instars) before becoming adults. Adults lay round or oval eggs on tree bark or in the webbing some species produce.
A ‘herd’ of immature barklice on a tree. Note how they do not have fully formed wings.
Photo: Herbert A. Pase III, Bugwood.org
Mature barklice on a tree. Note their fully formed wings.
Photo: David Coyle, Clemson Extension
Extensive webbing from barklice on tree branches.
Photo: Gerald J. Lenhard, Bugwood.org
Barklice feed on various organic materials such as mold, pollen, fragments of dead insects, algae, and lichens. Due to their inconspicuous nature, they are often unnoticed. However, two species that live in large groups are often noted in the southeastern United States due to their behavior. One species (Cerastipsocus venosus) found on the bark of trees moves as a group resembling a herd of animals or a flock of birds. Another species (Archipsocus nomas) makes silken webs on the bark of tree trunks and limbs. This webbing is most common in the coastal plain counties and appears in the late summer. The webbing from barklice is rarely found on the foliage, which differs from spider mites and certain caterpillars.
Management
Barklice are harmless; their presence only indicates that a suitable habitat exists in the area or on that tree. Even the webbing formed by some species causes no harm to the tree. In fact, the tree-dwelling species eat fungus, lichen, and organic debris and could be viewed as beneficial insects. Therefore, control of such insects is unnecessary; however, if you consider the webbing unsightly, you could use a high-pressure stream of water to remove it from the trees.
Originally published 02/08
