Bagworms: Are They Harmful and How Can I Get Rid of Them?

Bagworms: Are They Harmful and How Can I Get Rid of Them?

Seeing a butterfly emerge from its cocoon is magical. As it spreads its wings, you look in awe at the array of fluttering colors before you!

But, that sense of wonder doesn’t translate when a black, fuzzy moth emerges from its bag! Those moths, likely bagworms, were busy eating your evergreen or tree before making their debut.

Jodie H. saw them on her tree and asked, “My mimosa tree has bagworms. How do I get rid of them?”

Learn what bagworms look like, the damage they do to your trees and how you can control them below.

Bagworm Damage and Control

What do bagworms look like?

You probably won’t see the bagworms themselves, but instead, the 2” homes bagworms make in your trees. In the fall, the insects use their silk and pieces of the tree to create a camouflaged, cocoon-looking bag, which they fill with up to 1,000 eggs!

The eggs hatch in late spring or early summer, when super tiny, black larvae emerge. At 2 mm, they’re barely larger than a pinhead, which makes them light as a feather. The caterpillars use their silk thread as a parachute to travel to nearby trees and begin building a new home (or bag) there.

The pests hang out in their bags until late summer or early fall when the adult males emerge to mate. About the size of a quarter, male bagworms are ashy-black moths with transparent wings.

Where do bagworms come from?

They’re actually native to North America. But they’re mainly in the Eastern United States, dispersed all along the East Coast and in much of the Southeast.

What damage do bagworms do?

Bagworms will attack more than 120 different types of trees. Though, they prefer evergreens, like juniper, arborvitae, cedar and spruce.

Once they’ve found a tree to call home, bagworms start munching.

On evergreens, they’ll eat lots of the buds and foliage, causing branch tips to turn brown and then die. But if they eat more than 80 percent of the tree, the entire evergreen may die.

On deciduous trees (those that lose their leaves in winter), bagworms chew small holes in the leaves and can cause defoliation. Generally, these trees will bounce back if you get rid of the bagworms.

Bagworms also wrap silk around the twigs they build their bags on, which could kill the tree twigs a few years from now.

How can I get rid of bagworms on arborvitae, evergreens and other trees?

You aren’t going to like this, but the easiest way to remove bagworms is to cut off the bags by hand and destroy them. Be sure to cut off all their silk, too, because that could strangle (and kill) twigs later.

If that’s too gross or there are too many bagworms for you to remove, we can help! A certified arborist can apply a treatment to the tree when the larvae emerge in late spring or early summer.

Need to rid your tree of bagworms? Click here for a free consultation!

  • The Tree Doctor November 5, 2018 >Hi Marion, Sounds like you have a species of moth caterpillar in your garden. The term “bagworm” can mean different things to different people and can actually refer to several different groups of common caterpillars, depending on location. You may want to try a web search in your area on different caterpillars or find an insect hobbyist group in your area that may be able to help you identify the insect. Best of luck to you, Marion.
  • Marion Langham October 29, 2018 >I live in Kenya at the coast. In my garden we have worms that look just like the 'bag worm' I have never seen the tree with a 'bag'. Also we only have palm trees and Neem trees. I would send a picture but don't know how to to do that.
  • The Tree Doctor October 1, 2018 >Hi Mary, I would recommend having a certified arborist come out and inspect the tree. They can confirm there is indeed a bagworm infestation and can prescribe a treatment plan accordingly. Unfortunately, Davey Tree does not service your area. Here is a resource that can help you with hiring a certified arborist or reputable tree care company: Hopefully, this helps. Best of luck to you, Mary.
  • Mary Ballweg September 20, 2018 >Need help to get rid my the bag works on my blue spruce tree
  • The Tree Doctor September 12, 2018 >Hi Debbie, It appears that we do not currently service your area. We are really sorry about that. I definitely recommend having a certified arborist come out and inspect that tree. They will be able to make an accurate diagnosis and prescribe a treatment plan accordingly. Most reputable tree companies will send an arborist out to give you an estimate for free. Here is a resource that can help you with hiring a certified arborist or reputable tree care company: Best of luck to you, Debbie.
  • Debbie Hoselton September 11, 2018 >Hi! I have a silver maple you pruned a few years ago. It is now dropping leaves 2 months early with the black fungus on the leaves. We are collecting the leaving and getting rid of them. This tree is over 50 years old and umbrellas our backyard. Is this tree in jeopardy and what can be done to assure we will enjoy it for years to come!? Thank you!!!
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