Pin Oak Webs: Fall Webworm, Not Spiders—No Treatment Needed

Identification

Webs on leaf ends (not bark) + brown "seeds" inside = fall webworm (Hyphantria cunea). "Seeds" = frass (caterpillar droppings). Caterpillars have left; webs are abandoned.

Life Cycle

• Caterpillars feed June–Sept inside expanding webs.
• Drop to ground to pupate in soil.
• Adult moths emerge next spring; lay eggs on branches.

Impact

• Skeletonize leaves inside webs.
• May defoliate branches but rarely kill tree.
• Late-season defoliation = minimal energy loss (tree shutting down).

Management

None needed now. Caterpillars are gone. If webs return next summer:

• Prune out webs (small trees).
• Spray Bacillus thuringiensis (Bt) or spinosad when caterpillars small.
• Ignore on large trees—cosmetic only.

Fall webworm is native, cyclical, and rarely warrants intervention. Your oak will leaf out normally next spring.