Fall Webworm
Caterpillars that spin a loose gray web over the tip of a branch in late summer and feed inside it. The web gets bigger as they eat their way back down the branch.
Pest checklist
Four things to look for. If most of them match what you are holding, you are in the right place.
What gets rid of them
Gentlest option first. For most backyard cases the first one is enough, so try these in order and stop as soon as it works. If you do spray something, the product label tells you how — please read the notice further down.
1Leave them on a big tree
On an established shade or nut tree the damage is cosmetic and the webs weather off over winter.
Try this first2Cut out small webs
Prune off or twist out the web while it is still the size of a fist and drop it in soapy water.
3Open the web with a pole
Tear a hole in the webbing so birds, wasps and other predators can get to the caterpillars.
pole pruner extendable4Bt only if a young tree is being stripped
A Bt kurstaki spray works if you can wet the leaves the caterpillars are eating, which usually means opening the web first.
bacillus thuringiensis kurstaki bt spray5Do not burn them out
Burning webs out of a tree kills bark and branches that would otherwise have recovered fine.
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Which plants get fall webworm
Every plant we cover that gets fall webworm, grouped by type — tap any one to open its page. A note beside a plant came from that plant’s own entry, because the same pest can be a minor nuisance on one plant and a serious problem on another. Plenty of plants we do not cover get it too.
trees10
American Elm (Disease-Resistant)Ulmus americana
AppleMalus domestica
Black CherryPrunus serotina
Eastern RedbudCercis canadensis
MulberryMorus alba × rubra / M. rubra
PecanCarya illinoinensis
River BirchBetula nigra
Shagbark HickoryCarya ovata
SweetgumLiquidambar styraciflua
Weeping WillowSalix babylonica / alba hybrids
Plant families hit hardest
Related plants often share the same problems, so if one plant in a family has it, check the others. The largest group here is Juglandaceae, with 2 of the 10 affected plants.
- Juglandaceae2 plants
- Rosaceae2 plants
When to treat
Late summer, and most years you do not need to act. By the time these webs appear the tree has already stored its food for the year, so on an established tree this is a looks problem, not a health problem.
Timing only — the label is the law
This page tells you when to watch for fall webworm and when treating is worth considering. It is not a recommendation to apply any particular product. Read and follow the product label before you spray — under federal law the label is the legal instruction, and using a pesticide against it is illegal.
- Check the pre-harvest interval. Every product that’s cleared for an edible crop sets a minimum number of days between spraying and picking. Find it on the label before you spray anything you intend to eat.
- Check the re-entry interval before you or anyone else works in the treated area again, and use the protective equipment the label names.
- Confirm the product is registered for your crop in your state. This page groups many different crops together, and a product legal on one of them is not legal on all of them — state registrations differ too. Your state pesticide agency or local extension office can confirm both.
- Rates and mixing instructions come from the label, never from us. We don’t publish them because they differ by product and formulation.
Other problems on the same plants
If a plant gets fall webworm, these are the problems it most often gets as well, so they are worth checking for while you are out there. They tend to appear together; one does not cause another.