Oak Bark Lice: Beneficial Cleanup Crews

Thick silken webbing on oak trunk = bark lice (psocids/tree cattle). Harmless scavengers eating lichens, fungi, dead bark—not tree tissue.

Identification

• Fine silvery webbing on trunk/large limbs (not twigs/leaves)
• Tiny brownish-black insects (1/4") under webbing
• Group behavior = "tree cattle" nickname
• Wings roof-like over body, nymphs wingless

Ecological Role

• Consume excess lichens, dead bark, organic debris
• Population cycles: peak fall, decline winter
• No damage to living tissue
• Predators naturally regulate numbers

Management Options

• Do nothing: They disappear naturally
• Hose blast: Dislodges webbing if appearance bothers you
• No insecticides: Kills beneficials, unnecessary

These are nature's bark cleaners. Their presence indicates healthy bark ecology. Leave them be.