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Tree Cattle (Psocids): Harmless Bark Cleaners

What They Are

Psocids (tree cattle/bark lice) are tiny insects that spin fine silk webbing on trunks and feed on lichen, moss, algae, fungi, pollen, and insect remains.

Relationship

Psocids benefit: food and shelter.
Tree benefits minimally: bark cleaning.
Not obligate symbiosis—tree survives without them.

No Control Needed

Webbing disappears in weeks. If unsightly, blast with hose. Do not spray insecticides—they're beneficial.

Trees: Fine Webbing on Tree Trunks: Bark Lice (Psocids) Are Harmless; Tree Webbing Without Leaf Damage: Harmless Bark Lice (Psocids); Live Oak Galls & Webbing: Wasps & Bark Lice; Thick Webbing on Live Oak: Bark Lice (Psocids), Beneficial; Linden Tree Care: Gall Mites, Leaf Issues, and Treatment Options; Catalpa Near New Pavement: Monitor for Root/Canopy Conflict; Transplanted Chinese Maple Losing New Sprouts: Root Shock; Bark Lice on Oak Trees: Harmless Webbing; Oak Trunk Webbing: Harmless Bark Lice; Oak Bark Lice: Beneficial Cleanup Crews

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