By Amy DeYoung
Updated Oct 28, 2022
By Amy DeYoung
Updated Oct 28, 2022
Bagworms have a moderate to high damage potential for deciduous trees and shrubs. These destructive pests are fast breeders, making bagworm infestations challenging to control. To help, we’re shedding light on how you can get rid of bagworms before they destroy your plants.
Bagworms are part of the family Psychidae and feed on a massive variety of plants and many types of trees. The Thyridopteryx ephemeraeformis bagworm, also known as the common basket worm, common bagworm, or North American bagworm, feeds on over 50 families of evergreen and deciduous trees.
After bagworm larvae feed on trees and plants, they’ll encase themselves in a cocoon-like bag made from leaves, twigs, and self-spun silk. Once inside the bag, female bagworms will lay eggs, often 500 to 1,000 at a time. Every bagworm egg hatches into a new bagworm, quickly causing a significant problem for your foliage. During fall, adult male bagworms emerge from the bagworm bags after female bagworms release pheromones to attract mates, starting the bagworm life cycle over once more.
As adults, female bagworms have no wings and resemble maggots. In contrast, male bagworms transform into male moths with transparent wings.
Here are some of the most common signs of bagworm infestations:
However, several pests can cause similar problems.
Gypsy moths may also defoliate Christmas and pine trees. You may spot snailcase bagworms, plaster bagworms, and grass bagworms on conifers, but these insects won’t damage your trees. Certain species of birds, like sparrows, are foragers who may feed on fruit, crops, blossoms, and buds on your plant, damaging the plant in the process. However, it’s uncommon for birds to cause brown spots on foliage.
If you have a small bagworm population, put on gloves and begin handpicking the bagworm bags off the plants. Submerge the bags immediately into a bucket of soapy water to suffocate and kill the larvae.
Keep in mind that this will only work if you catch the infestation early on and the larvae haven’t left the bags yet. Hatching typically takes place from May to early June, so handpicking will only be effective from late fall to early spring.
Another effective pest control method is changing the environment to make it less desirable for pests. For example, you could attract sparrows, which are common bagworm predators. To attract birds, consider purchasing a birdbath that is low to the ground.
An alternative method is using bacteria, specifically Bacillus thuringiensis, which kills bagworms as soon as the eggs hatch. This method must be timed well because the bacteria won’t be strong enough to kill larger larvae. Purchase the bacteria at your local garden store or Amazon and apply with a garden sprayer, paying close attention to the application instructions. Reapply this product every seven to 10 days until the bagworm bags are gone and your plants are returning to their original healthy state.
Insecticides with diazinon, carbaryl, or malathion are effective against bagworm problems. These pesticides are applied directly to your shrubs and trees when worms are still young larvae, around late May. Follow the specific insecticide’s instructions for the best results.
Regularly clear debris under trees and shrubs, such as leaves, twigs, and pine cones, to prevent bagworms. This process will remove larvae and eggs, preventing large infestations. Always burn the debris or seal it into a tight bag to ensure the bagworms cannot escape.
Trichogramma wasps can be purchased at many garden centers or online. They’re parasitic wasps that lay eggs inside the eggs of bagworms. Then, the wasp larvae will feed on baby bagworms, preventing the infestation from starting.
These parasitic wasps are easy to use and effective. However, if you or a loved one have an allergy to wasps, we recommend considering other options.
Neem oil is a popular and natural remedy for eliminating pests, such as aphids, bagworms, spider mites, and even wasps.
Purchase neem oil from your local garden center or online as a concentrate. Then, mix with a combination of liquid soap and water to create a homemade repellent. Spray onto affected plants.
Spinosad is a product created from soil bacteria that is fermented. It’s a natural and effective remedy against many types of pests. Purchase spinosad in a concentrated form, then follow the product’s instructions closely for the best results.
Certain plants are known to repel moths, and preventing moths will reduce the number of bagworms later on, making this method a great long-term pest control investment.
Plants that are known to repel moths include thyme, chrysanthemum, citronella, rosemary, eucalyptus, lemongrass, and marigold. Place these plants throughout the yard and close to trees and shrubs, which are a bagworm’s preferred living area.
Moths are attracted to lights, mainly when it’s dark outside, and your house or backyard is the only lit-up area. Turn off your patio lights as much as possible and limit outdoor lighting.
Remember, the fewer moths you have around, the fewer bagworms you’ll be dealing with later on.
Bagworms can be a serious issue for your beautiful shrubs and trees. Fortunately, there are many steps you can take to prevent and get rid of bagworms currently on your trees. Take a few different steps today to start tackling the problem before your trees and shrubs become sickly or die. Once you’ve applied a treatment, made some environmental changes, and reduced the number of moths flocking to your yard, keep up with your lawn care for the best, long-term results.
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