Tree problems · Insect
Bagworms: signs and what to do
Bagworms is an insect pest, often seen on eastern red cedar, arborvitae, leyland cypress. Look for: small cone-shaped bags hanging from branches, made of silk and bits of leaf or needle.
General information, not a diagnosis. A certified arborist or your county extension office can confirm.
- Insect
- Eastern red cedar
- Arborvitae
- Leyland cypress
- Pines
- Spruces
- Bald cypress
Signs to look for
Tick what you see. More ticks make it more likely, but only an on-site look can confirm.
0 of 6 signs ticked. Ticks stay in this browser only.
Season
Eggs overwinter in the bag on the tree and hatch in late spring. Young caterpillars build tiny bags and feed through the summer. There is one generation a year.
How it spreads
Hatchlings can drift on silk threads to nearby plants. Spread to new places usually happens through short moves and the movement of infested plants.
Where it is found
Bagworms are native to North America and are found in many parts of the eastern and central United States. Check your state official map; ranges change.
Official sources
What to do
- 1
Pick off bags by hand and drop them in a bucket of soapy water. Winter and early spring are good times, before the eggs hatch.
- 2
Check conifers closely. Evergreens do not regrow the needles that bagworms eat, so act early.
- 3
For many bags, ask a licensed applicator about a spray in late spring to early summer, while the bags are still small.
- 4
Reduced-risk products, such as Bt, may help on young caterpillars but can need repeat sprays. Follow the label.
- 5
After the caterpillars are grown, sprays are generally no longer practical, so do not wait.
Safety first: do not climb, do not cut near power lines and do not use a chainsaw on storm-loaded wood. Call the utility for downed lines and 911 if anyone is in danger.
Prevention
Check evergreens each spring and summer. Hand-pick bags when you see only a few. Keep trees watered so they can handle some feeding. Birds and parasitic wasps help keep numbers down, so avoid broad sprays that kill them.
When to call a pro
Call a pro if you see many bags, if the tree is tall, or if more than a small part of the tree has brown needles. Early help can save an evergreen.
Not sure who to call? Read how to hire a tree service or check is my tree dangerous?
Trees it affects
Usually seen on: Eastern red cedar, Arborvitae, Leyland cypress, Pines, Spruces, Bald cypress, Black locust, Honeylocust, Many other trees and shrubs.
- Eastern Red Cedar
- Arborvitae
- Leyland Cypress
- Eastern White Pine
- Colorado Blue Spruce
- Norway Spruce
- Bald Cypress
- Black Locust
- Honeylocust
- American sycamore
See all species in our tree library, or pick a tougher tree with the tree picker.
For tree companies
How to explain bagworms to a customer
Tell the owner that bags are easy to miss, and that on evergreens the damage cannot grow back. Explain that timing is the whole game: small bags in late spring are much easier to treat. Quote a hand-picking job for small trees and a spray job for large ones.
Send this page to the customer after your visit so they can read the signs in plain words. See also selling plant health care and the job photo checklist.
Questions
What do bagworm bags look like?
They look like small cones or tiny pine cones hanging from branches. They are made of silk with bits of leaf or needle stuck on the outside.
Can bagworms kill a tree?
They can kill evergreens such as arborvitae and juniper if they strip most of the foliage, because the needles do not grow back. Deciduous trees usually recover.
Should I remove bags in winter?
Yes, if you can. Winter bags hold the eggs for next year. Drop them in soapy water, since a bag left on the ground can still hatch.
When is the best time to spray?
Extension sources point to late May through mid-June in many areas, while the bags are small. Local timing varies, so ask your county extension office.
Do natural enemies help?
Yes. Birds, parasitic wasps and flies help control bagworms. Avoid broad-spectrum sprays when you can, so those helpers survive.
Will bagworms come back every year?
They can. Females lay eggs in the bag, so any bag left on the tree can start next year's problem. Remove bags and check each year.
Can Lirevon diagnose bagworms on my tree?
No. Lirevon is a remote marketing team for tree service companies and does not do tree work. This page is general information, not a diagnosis. A certified arborist or your county extension office can confirm what is wrong with your tree.
How do I find a good local pro for this?
Search Google Maps for certified arborists or tree services near you, read their reviews and ask for proof of insurance. Get two or three written quotes. Our guide on how to hire a tree service lists the questions to ask.
Related tree problems
- Spider mites (Insect)
- Cankers (Disease)
- Girdling Roots (Other damage)
- Road salt damage (Other damage)
- Drought Stress (Other damage)
- Herbicide damage (Other damage)