Webs Covering Oak Tree—Not Webworms: Spider Mites

Oak tree leaves wilting, discolored. Two days later, 60% covered in webs. Tiny (1 mm) fast insects inside, abdomen 2x thorax, not ants/worms. Second oak 6 ft away unaffected.

Diagnosis: Spider Mites (Likely Oligonychus spp.)

• Microscopic arachnids, suck chlorophyll from leaves.
• Produce fine silk webbing on leaves/branches (not tents like webworms).
• Thrive in hot, dry, dusty conditions—drought-stressed trees.
• Abdomens larger than thorax; colors vary (red, green, yellow).

Management for Large Trees

• Water deeply weekly during drought—reduces stress, washes mites off.
• Hose off foliage with strong jet (morning, weekly).
• Insecticidal soap/horticultural oil if reachable (small trees only).
• Avoid broad-spectrum insecticides—kill predatory mites that control them.

Large oaks usually survive; recovery may take a year+. Monitor the second tree.