Fall Webworm

Hyphantria cunea

Insectalso: Webworm

A late-summer caterpillar that wraps the tips of tree branches in messy silken webs and feeds on the leaves inside. Fall webworm attacks a huge range of trees, and while the webs are unsightly, the late-season feeding rarely harms an established tree because the leaves have already done most of their work for the year.

🔎 How to spot it

Look for loose, dirty silken webs enclosing the leaves at the ends of branches in mid to late summer and fall, filled with caterpillars, droppings, and shed skins. The caterpillars are pale green to yellow and very hairy, with a dark or yellowish stripe down the back and tufts of long white hairs from black and orange bumps. Unlike tent caterpillars, the webs are at the branch tips, not in the forks.

🥀 Damage it causes

The caterpillars feed on the leaves inside the expanding web, skeletonizing and consuming them, but because they feed late in the season, after the leaves have fueled the tree for most of the year, the damage to established trees is largely cosmetic. The webs are unattractive, but the tree is rarely seriously harmed and leafs out normally the next spring.

🛡️ Prevent it

Tolerate light infestations on large trees, since they do little real harm and natural enemies, birds, predators, and parasitic wasps, usually keep numbers down. On small trees, scout in summer for the first small webs at branch tips and prune them out early. Keeping trees healthy helps them shrug off the late feeding.

🧯 If it is already here

Prune out and destroy the webbed branch tips on small trees while the webs are still small, or open the webs with a pole so birds and predators can reach the caterpillars. On accessible small trees, the organic sprays Bacillus thuringiensis (Bt) or spinosad control young caterpillars. Burning the webs is not recommended, as it damages the tree.

💡 Good to know

Fall webworm is easy to confuse with eastern tent caterpillar, but the season and location of the web tell them apart: fall webworm webs come late and sit at the branch tips, while tent caterpillar tents come in spring and sit in the branch forks. On a big shade tree, fall webworm is best simply ignored.

🌱 Plants it attacks

61 plants in the library can be attacked by this pest

For educational and informational purposes only. Pest control advice is general guidance drawn from university cooperative extension sources; always identify a pest positively and read and follow the label on any product before use, especially around food crops, children, and pets.