Fall webworms are one of the most visible tree pests in Texas, spinning large silky webs over branch tips from late summer through fall. While the webs look alarming, especially when they stretch several feet across, webworms rarely cause lasting damage to healthy trees. The caterpillars feed on leaves inside those webs, and most trees recover fully the following spring.
What Fall Webworms Look Like
The caterpillars grow to about 1 inch long and have black or reddish heads with pale yellow or greenish bodies. A broad mottled stripe runs down the back, containing two rows of black bumps (one pair per body segment), with yellowish patterns along the sides. Tufts of long whitish hairs cover their bodies, giving them a fuzzy appearance. The adult moths are mostly white with dark spots on the wings. Females lay eggs in masses on the undersides of leaves, and the egg clusters appear covered in fine hair.
Once the eggs hatch, caterpillars immediately begin spinning silk over nearby leaves. As the colony grows, the web expands to cover leaf clusters or entire branch sections, sometimes reaching several feet in diameter. A single web can contain dozens of hairy caterpillars, all hatched from one egg mass.
Webworms vs. Tent Caterpillars
Texans often confuse fall webworms with eastern tent caterpillars, but the two are easy to tell apart once you know what to look for. Fall webworms build their webs at the tips of branches, enclosing the leaves they feed on inside the silk. Eastern tent caterpillars do the opposite: they spin webs in the crotches of tree branches and leave the nest to feed on surrounding foliage. Timing also differs. Tent caterpillars appear in early spring, while fall webworms show up in late summer and fall.
Which Trees They Target
Fall webworms are generalists that feed on more than 100 species of deciduous trees, but in Texas they have clear favorites. Pecans, walnuts, persimmons, sweetgums, and hickories are hit hardest. You’ll also see webs on elms, mulberries, and various fruit trees. Pecans are a particular concern for Texas landowners because heavy defoliation late in the growing season can interfere with nut development, reducing the size and quality of that year’s crop.
For most shade trees, even significant leaf loss from webworms is cosmetic. The feeding happens late enough in the year that trees have already stored much of the energy they need. A healthy tree will leaf out normally the next spring. Repeated heavy infestations over multiple years can stress a tree, but this is uncommon when natural predators are present.
Life Cycle and Timing in Texas
Fall webworms typically produce two generations per year in most of Texas, though southern parts of the state can see three. The first generation appears in late spring or early summer, often going unnoticed because the webs are small and scattered. The second generation, arriving in August and September, is far more conspicuous. Warm temperatures accelerate development, and the larger caterpillar populations produce the massive webs that catch your eye from the road.
After feeding for four to six weeks, the caterpillars drop to the ground and pupate in the soil or leaf litter, overwintering as pupae until the following spring. The adult moths emerge, mate, and the cycle begins again.
Natural Controls That Keep Them in Check
Webworm populations are regulated by a long list of natural enemies. Parasitic wasps lay eggs inside webworm caterpillars, and predatory insects like paper wasps tear open webs to feed on the larvae. Birds, particularly cuckoos and vireos, are effective webworm predators. In most years, these natural controls prevent outbreaks from becoming severe. This is one reason entomologists generally recommend tolerating webworms when possible: spraying broad-spectrum insecticides kills the predators and parasites that would otherwise keep the next generation in check.
Manual Removal
For individual trees in your yard, physical removal is the simplest and most effective approach. Use a pole pruner or long stick to tear open or pull down webs while the caterpillars are still small. Exposing the larvae to predators and weather is often enough to end the colony. If you prune out a web-covered branch, bag and dispose of it rather than leaving it on the ground where caterpillars can crawl to another tree.
Hand-picking caterpillars or destroying their webs can significantly reduce a local population, according to the Texas A&M Forest Service. You don’t need to remove every web on a large tree. Focus on branches where the webs are still compact and growing. Once a web has turned brown and dried out, the caterpillars have already finished feeding and moved on.
When and How to Spray
If you have a high-value tree with a heavy infestation, or a pecan tree where you want to protect the nut crop, targeted spraying can help. Two biological insecticides are recommended by Texas A&M AgriLife Extension: Bt (a naturally occurring soil bacterium that kills caterpillars) and spinosad (derived from another soil organism). Both are effective against webworms and safe for beneficial insects like bees and parasitic wasps.
Timing matters more than product choice. Apply when the webs and caterpillars are still small, ideally when webs are the size of a softball or smaller. Larger webs are harder to penetrate, and older caterpillars are more resistant. Because webworm larvae stay inside their silk enclosure, any spray needs to physically penetrate the web to reach them. Use enough pressure and volume to soak through the silk, or tear the web open before spraying. A garden hose-end sprayer can work for trees within reach, but tall pecans and shade trees may require professional equipment.
Broad-spectrum chemical insecticides are available but generally unnecessary for webworms. They kill the natural predators that help control future generations, potentially making next year’s problem worse. If you choose this route, apply it directly to the web rather than blanket-spraying the entire tree canopy.
Do Webworms Kill Trees?
Almost never. Fall webworms are a nuisance pest, not a tree killer. Even when webs cover what looks like half the canopy, the actual leaf area consumed is a small fraction of the tree’s total foliage. The damage looks worse than it is because the webs are so visible, turning brown and papery as they fill with frass and shed skins. Healthy, well-watered trees tolerate defoliation without long-term consequences.
The main exception is trees already under stress from drought, disease, or construction damage. A stressed tree that loses significant foliage to webworms may struggle to recover, particularly if the infestation repeats for several consecutive years. Keeping your trees healthy through proper watering and mulching is the best long-term defense against any defoliating pest.