Silky Webbing on Oak Tree: Harmless Bark Lice (Psocids)

An oak tree, struck by lightning 14 years ago with a resulting cavity, is suddenly covered in formless silky webbing on trunk and branches. No insects are visible at the bottom. The owner wants to know what it is and if it's harmful.

Identification: Bark Lice (Psocids)

The webbing is produced by bark lice (also called Psocids or "tree cattle"). They are not pests—they feed on lichens, fungi, dead bark, and organic debris on the bark surface.

Key Characteristics

• Fine, silvery webbing on trunk and large limbs (not on twigs/leaves).
• Hundreds of tiny insects may be under the webbing.
• Common along Gulf and Atlantic coasts (Texas to South Carolina).
• Populations peak in fall; decline in winter.

Management

No control needed. They are beneficial scavengers. If webbing is objectionable, a strong water blast will dislodge them. Insecticides are unnecessary and harm beneficials.