Fall Webworm: Atlanta Diagnosis & Treatment Guide

What Are Fall Webworms?

Fall webworms (Hyphantria cunea) are native caterpillars that spin conspicuous silken webs or "tents" at the ends of tree branches in late summer and fall. Unlike the spring-active eastern tent caterpillar (which builds webs in branch crotches), fall webworms create their nests at branch tips and progressively enlarge them as they feed on enclosed foliage. The webs can become quite large and unsightly, sometimes enveloping several feet of branch length.

Despite their alarming appearance, fall webworms are generally a cosmetic pest rather than a tree health threat. They appear late enough in the growing season that the trees have already completed most of their annual photosynthesis. Healthy, mature trees shrug off webworm defoliation with no lasting harm.

How to Identify Fall Webworms

• Silken webs at branch tips: The webs appear in mid to late summer and are positioned at the ends of branches (not in branch crotches like tent caterpillars). Webs are loosely woven and may contain frass (caterpillar droppings) and skeletonized leaves.
• Defoliation within webs: Caterpillars feed on leaves enclosed by the web, gradually expanding the web to reach fresh foliage.
• Caterpillars: Pale yellowish or greenish caterpillars with long white hairs are visible inside the webs. Mature larvae are about an inch long.
• Multiple webs per tree: Heavy infestations can produce dozens of webs throughout the canopy, creating a dramatic but largely harmless display.

Which Atlanta Trees Are Most Susceptible?

• Pecan: A favored host. Pecans in Atlanta commonly display fall webworm nests in August and September.
• Sweetgum: Another frequent host in the Atlanta area.

Fall webworms are generalists that feed on over 100 tree species. In Atlanta, you may also find them on persimmon, sourwood, and various ornamental trees.

Treatment Options

• Physical removal: For accessible webs, simply break open the web with a stick or pole and expose the caterpillars to birds and predatory wasps. This is the most practical approach for most homeowners.
• Pruning out webs: Small webs on minor branches can be pruned out and disposed of. Avoid removing large branches solely to eliminate webs—the tree damage from improper pruning exceeds any webworm damage.
• Bt sprays: If control is desired on young or stressed trees, Bacillus thuringiensis sprays applied to the web surface are effective against young caterpillars. Spray must penetrate the web to reach the larvae.
• Do nothing: For healthy, mature trees, the best management is often no management. The trees will leaf out normally the following spring.

Prevention Strategies

• Monitor in late summer: Check susceptible trees in July and August for early web formation. Small webs are easier to remove than large ones.
• Maintain tree health: Healthy trees tolerate webworm defoliation better than stressed trees. Proper plant health care and watering give trees resilience.
• Encourage natural enemies: Paper wasps, parasitic flies, and birds are important webworm predators. Breaking open webs exposes caterpillars to these natural controls.

When to Call an Arborist

Fall webworms rarely warrant professional treatment on established trees. Consider calling an arborist if: a young or recently transplanted tree is heavily infested, the tree is already stressed by other factors, or you simply want a professional assessment. For trees with persistent annual infestations, professional pruning to reduce canopy density can make trees somewhat less attractive to egg-laying adult moths.

Atlanta-Specific Considerations

Atlanta typically sees two generations of fall webworms per year—one in early summer and a larger, more noticeable generation in late summer and fall. The warm climate allows both generations to complete their development, resulting in more conspicuous webbing than in northern regions that experience only one generation.

Atlanta homeowners frequently mistake fall webworms for tent caterpillars or confuse them with more damaging pest problems. The key distinction is timing (fall webworms appear in summer/fall, not spring) and location (branch tips, not crotches). If you are unsure whether the webs on your trees are cause for concern, EastLake Tree Services can provide a quick assessment. Call 404-850-1174.