Bagworms
Spindle-shaped bags an inch or two long, shingled with bits of the very plant they hang from, dangling like ornaments on evergreens. The caterpillar inside strips foliage as it grows; heavy years can brown out whole arborvitae.
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.
1Hand-pick the bags in winter
Each overwintering bag holds hundreds of eggs; picking them off by hand before spring is the single most effective move.
Try this first2Bt in early summer
Works only on the young caterpillars, typically June — once bags pass an inch it is too late for the season.
bt spray caterpillars thuricide
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Which plants get bagworms
Every plant we cover that gets bagworms, 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.
trees4
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 Cupressaceae, with 4 of the 5 affected plants.
- Cupressaceae4 plants
When to treat
Treat in early summer while the caterpillars are still small. Once the bags harden, hand-picking in winter is all that works.
On specific plants
- Growing
- Bagworm patrol in June; site away from apples/serviceberry or accept rust rings.
Timing only — the label is the law
This page tells you when to watch for bagworms 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 bagworms, 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.