How to Get Rid of Bagworms Safely
Got the Bagworm Blues?
If you live in the eastern U.S., you've probably seen your share of bagworms (Thyridopteryx ephemeraeformis). It's not uncommon for large infestations to plague forestland along neglected roadways or, if you're unlucky, within your own landscape.
Bagworms spin cobweb-like "bags" in trees and shrubs. They particularly like to infest conifers such as pine, cedar, arborvitae, Leyland cypress, and juniper. Sometimes, they're so prolific that they kill their host tree. Because the bags are shaped like pine cones, they often pass unnoticed in conifers—until it's too late.
Bagworms may also spin cocoon-like nests in deciduous trees, such as locust, maple, linden, sycamore, and boxelder. Although these trees may suffer damage, they're rarely killed by bagworms. Nevertheless, few homeowners want even one bagworm nest in their yard.
Where Do Bagworms Come From?
Bagworms are actually moths in their larval (caterpillar) stage of development. After hatching, moth caterpillars spin cocoon-like bags. These bags have pieces of leaves from the plants they're feeding upon attached to them.
At first, the bags are very small—only about 1/8 inch long. The young bagworms move about freely as they feed, carrying their bags with them, enlarging them as they themselves grow bigger.
It's at this point—when moth caterpillars are young—that they're easiest to destroy through the application of a bacteria commonly called BT.
How to Get Rid of Bagworms
Bacillus thuringiensis (BT) is a bacteria that kills certain insects, including bagworms, but doesn't adversely affect humans or other animals.
BT works extremely well against young moth caterpillars. So if you're going to use BT, be sure to apply it early. Common brand names of products that contain BT include Dipel, Caterpillar Killer, and Thuricide.
These insecticides are also labelled for bagworm management: Bifenthrin Pro Multi-Insecticide, Onyx Insecticide, Talstar F, Talstar Lawn & Tree Flowable, Talstar GC Flowable, TalstarOne Multi-Insecticide, and Dursban 50W.
Like BT, they should be applied shortly after the moth eggs hatch.
Removing bagworm bags from trees by hand isn't as gross as it sounds. Remove the bags in winter or early spring (before the moth eggs hatch) and destroy them.
How NOT to Get Rid of Bagworms
You may have heard of gardeners pouring gasoline on bagworm bags and then setting them on fire. It's a dangerous practice that could cause serious damage to you, your tree, and your property. Don't try it!
Stick with handpicking the bags when the eggs are dormant. Or, if your infestation is severe, opt for BT or some other non-petroleum chemical solution. Those are the best ways to beat the bagworm blues.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Questions & Answers
What should you do with bag worms that are emerging from a pod? I tied them in a bag and open garbage can, but some escaped. I had even tied the bag shut.
At least you removed some. That will definitely mitigate the damage they could have done.Helpful 6
I just realized that I have these things in a spruce. I don't see them in any of my other trees. Can I just cut this tree down and burn it? Will that get rid of them?
That would work for that spruce, but it would be like killing the patient to get rid of the disease. And chances are a few bagworms are on other trees, too. While weeding the other day, I found one hanging from a solar light! I prefer handpicking them, but you may want to use two methods if you just can't tolerate any bagworms at all on your trees. You could also do some judicious pruning.Helpful 2