Controlling Fall Webworms in Pecan Trees

Identifying the Pest

What many call "bagworms" on pecans are usually fall webworms (Hyphantria cunea). These caterpillars create conspicuous silk webs on branch tips and feed on leaves.

Life Cycle & Timing

Overwintering pupae emerge as moths in spring, laying egg clusters on leaves. First-generation larvae appear in early summer, often going unnoticed. A second, larger generation in midsummer causes significant defoliation.

Integrated Management Strategies

• Sanitation (Winter/Early Spring): Remove fallen leaves, debris, and old mulch where pupae hide. Replace with fresh mulch.
• Egg Scouting: Inspect leaf undersides for greenish, woolly egg masses from late spring through fall. Destroy affected leaves—impractical for tall trees.
• Biological Control (Bt): Apply Bacillus thuringiensis (Bt) spray or dust to foliage near webs at first sign of hatching. Reapply every 2 days while larvae emerge. Bt spares bees and mammals but affects all caterpillars.
• Mechanical Removal: Clip and burn infested branches or drown larvae in soapy water. A pole pruner reaches webs up to 16 feet.
• Chemical Options (if webs present): Acephate (Orthene), carbaryl (Sevin), or bifenthrin (Talstar) applied to adjacent foliage.

Year-Round Vigilance

Because webworms persist in various stages year-round, combine tactics for best results. Early intervention with Bt is most effective and environmentally friendly.