How to Get Rid of Bagworms
If You've Got Bagworms on Trees, Make Sure to Remove Them Early and Often
You may be wondering how to get rid of bagworms that you’re finding on trees in your yard. The first step is to make sure what you’re seeing is actually evidence of a bagworm. An easy way to tell is if you look at your trees and you find small pinecone-shaped sacks hanging from the branches. In my neck of the woods, these are the sacks of the Evergreen bagworm (Thyridopteryx ephemeraeformis) also known as the Eastern bagworm or common bagworm.
Don’t confuse bagworms with tent caterpillars. They are two different species. But sometimes people mistakenly call tent caterpillars bagworms since tent caterpillars make fine mesh sacks that look like bags hanging from tree branches.
What are Bagworms and How do they Live?
Before we talk about getting rid of them, it’s fun to learn a little bit about bagworms. First of all, their name reflects the life cycle where they are seen the most; as a larvae. These, in fact, are not true worms at all. They are actually small moths in their larvae form.
Bagworms belong to a family of moths that are found throughout the world. They are also referred to as case moths which is relevant considering they make a case to live. Here’s how their fascinating life cycle works.
From early April through June, the eggs hatch and emerge from the carcass of their mother in the same case that she used. They remind me of spiders at this point because they crawl out of the bottom of the case and drop a strand of silk which carries them to other plants in the area.
In their new homes, the larvae start to weave their own case out of silk and then add some decorating touches like bits of needles and branches from around them; whatever’s handy. This is a great camouflage technique considering birds are always on the lookout for a protein packed meal and bagworms hit the spot.
As the caterpillars grow, they are not stationary. They stick their heads out of their cases and walk around with their camouflaged case on their back, munching on the plants around them. In severe cases, this can lead to death for the host tree.
Just like we learn about in grade school science class, moths do have a life cycle. So around August, the mature caterpillars will anchor themselves, along with their cases, to a tree branch using silk webbing to hang securely. Once they’ve finished pupating, the males will leave their cases. They kind of look like a bee with a furry body and very short stubby wings. The females, once mature, do not leave their cases. The males fly to the females. They will mate and the females will lay their fertilized eggs in their cases.
Bagworms love arborvitae and red cedar, but they will also eat from juniper, black locust, oak, sycamore, pine, spruce and more.
How to Get Rid of Bagworms
As homesteaders living on largely undeveloped land, bagworms aren’t generally a problem. So there are usually no worries on the larger homestead about how to get rid of them. Bagworms are naturally occurring pests and in undisturbed nature, there is normally a balance that keeps their numbers in check.
In more urban and suburban areas, they can become pests and many folks wonder about how to get rid of bagworms since they do cause tree damage. In those areas, predators for bagworms are not a part of the equation since natural pest control for gardens usually consists of insecticides which kill good and bad insects alike. Also, woodpeckers and sapsuckers (major bagworm predators) are rarely found since tree snags (dead trees with parts still standing) and cavities in larger trees aren’t available.
If you live in urban and suburban areas and use natural ways to get rid of mice and natural pesticides for gardens you may find that bagworms aren’t as much of a problem for you as for others since you may still have a few natural predators around.
The best way to rid your trees of bagworms is to hand pick them from the trees. You can do this in the spring before the larvae hatch and in the fall and winter when the bags are more easily spotted. As you’re hand picking, I find it’s best to use a pair of scissors to cut the silk that binds the bagworm case to the tree. The cases can be surprisingly strong and you can do serious damage to your tree by pulling too hard.
Wasps and hornets are also natural predators of the bagworm so there are gardeners who have had success introducing ichneumonid wasps to their infected areas. These wasps will parasitize the bagworms and take care of your problem.
Have you struggled with how to get rid of bagworms and found a solution that works for you? Let us know in the comments below.
Originally published in 2016 and regularly vetted for accuracy.