Fall Webworm: Atlanta Diagnosis & Treatment Guide

What Is Fall Webworm?

Fall webworm is the larval (caterpillar) stage of a native moth, Hyphantria cunea, that builds large silken webs at the tips of tree branches and feeds on the leaves enclosed inside. It is a widespread defoliator of hardwood trees across Georgia and the southeastern United States.

How to Recognize It

• Large, dirty white silken webs wrapped around the ends of branches, often starting small in midsummer and expanding through fall.
• Hairy caterpillars about one inch long, pale yellow to greenish with dark stripes and a black or reddish head, feeding inside the webs.
• Leaves inside the webs chewed down to the veins or completely stripped, leaving brown, skeletonized foliage.
• Webs that grow larger over time as the caterpillars expand them to reach fresh leaves.
• Frass (caterpillar droppings) and dead leaf fragments collecting inside the webbing.
• Multiple webs appearing on the same tree, sometimes in successive waves through the season.

Webs typically begin appearing in mid to late summer and become most visible from August through October across the Atlanta area. The southeastern climate supports two to five overlapping generations per year, so new webs can keep showing up well into fall.

Why It Matters for Atlanta Trees

For most established, healthy shade trees, fall webworm is more of a cosmetic problem than a true threat, because the defoliation happens late in the growing season after the tree has already stored most of its energy. Heavy or repeated infestations on young trees, recently transplanted trees, or trees already stressed by drought, construction damage, or other pests can weaken them and make them more vulnerable to decline, and catching infestations early keeps the webs (and the damage) from spreading across the canopy. In Atlanta yards, the trees most often affected include pecan, hickory, black walnut, persimmon, sweetgum, maple, river birch, wild cherry, crabapple, sourwood, and American beech.

General Prevention

• Keep trees vigorous with proper watering during dry spells and a 2 to 4 inch layer of mulch over the root zone (kept off the trunk), since healthy trees recover from defoliation more easily.
• Scout trees from midsummer onward and prune out small webs while they are still within easy reach, before the caterpillars expand them further.
• Disturb webs with a long pole or rake so birds, wasps, and other natural predators can reach the caterpillars inside.
• Avoid broad-spectrum yard sprays that kill the parasitic wasps, spiders, and predatory insects that naturally keep fall webworm populations in check.

What NOT to Do

• Do not self-diagnose. Many tree problems look alike, and treating the wrong one wastes time and can harm the tree.
• Do not apply fungicides, insecticides, or other chemicals without an arborist's specific recommendation. Wrong product or wrong timing makes things worse.
• Do not burn webs out of trees with torches or flaming rags. This is a common folk remedy that causes far more harm to the bark, cambium, and live branches than the caterpillars themselves ever would.

Related Services

For most diagnosis and treatment questions, the right starting point is one of our services:

• ISA-Certified Arborist Services for diagnosis, consultation, and a second opinion.
• Plant Health Care (PHC) for ongoing tree health management.
• TRAQ Tree Risk Assessment when the tree may be a safety hazard.

Sources

This page summarizes general information from: UGA Extension (Landscape Pest Management), UGA Cooperative Extension Publication C1197, and Clemson Cooperative Extension Home & Garden Information Center.