Bagworms are common landscape pests that can wreak havoc on your ornamental plants, especially conifers. They’re notorious for stripping trees and shrubs bare, and if left untreated, they can cause serious damage.
Finding bagworms early is key to controlling them. This article will give you a complete guide to identifying, monitoring, and, most importantly, finding the best treatment for bagworms before they do too much damage to your yard.
Identifying Bagworms and Understanding Their Life Cycle
Bagworms are relatively easy to spot because of their unique appearance. They construct cone-shaped bags around themselves, ranging in size from a quarter of an inch to more than two inches long.
These bags are made from silk and bits of foliage, so they tend to blend in with their surroundings. This camouflage can make them difficult to distinguish from other pests or even from parts of the tree itself.
Bagworms are most active and cause the most damage early in the summer. Female bagworms lay a lot of eggs—as many as 500 to 1,000—inside the bag. The caterpillars then emerge and start feeding heavily on the tree’s foliage.
How to find bagworms
It’s important to check your plants for bagworms regularly, especially in the late winter and early spring. The sooner you find them, the easier they are to get rid of.
Pay close attention to plants bagworms love, such as evergreens. Look for small, tell-tale bags attached to twigs and branches.
Other warning signs include localized defoliation and brown spots on the leaves.
Cultural Control Methods for Bagworms
There are several ways to deal with bagworms that don’t involve pesticides.
Handpicking and Pruning
One way to control bagworms is to physically remove and dispose of them. You can prune infested branches or handpick the bags, using a sharp knife to slice the silk band that attaches the bag to the branch.
It’s important to dispose of the bags properly to keep the bagworms from re-infesting your trees and shrubs. One option is to keep the removed bags in a dry, open container, which allows any parasites inside to emerge and attack other bagworms.
Promoting Healthy Plants
Another cultural control method is to plant tree species that are naturally resistant to bagworms. Healthy plants are also better able to withstand bagworm damage, so be sure to water, fertilize, and prune your trees appropriately.
Chemical Control Methods for Bagworms
If you’ve got a serious infestation of bagworms, you may need to turn to chemical controls to get them under control. Keep in mind that timing is everything.
Timing of application
Insecticides are most effective when bagworms are in their early stages, typically late May or early June. If you have evergreens, that’s the time to treat them. Later in the season, once the bagworms have stopped feeding, chemical treatments won’t be as effective.
Insecticide options
There are several insecticides that work well to control bagworms. These include Bacillus thuringiensis (Bt), spinosad, permethrin, and acephate. You can spray with pyrethroids like permethrin or bifenthrin in late May or early June when the caterpillars are tiny.
Be sure to follow the label instructions carefully when you’re applying these products. Consider the effects of these chemicals on beneficial insects and the environment.
Repeat treatments
To manage bagworms effectively, you’ll probably need to treat your trees and shrubs more than once. Plan to treat again next year in mid-May to target the newly hatched caterpillars.
Integrated Pest Management (IPM)
Integrated Pest Management, or IPM, is a way of managing pests by combining different strategies.
The idea is to use cultural controls to prevent infestations whenever possible. Cultural controls reduce the need for harsher chemical treatments. But sometimes, you may need to use chemicals. If so, IPM recommends applying chemical treatments strategically.
Also, it’s important to remember that a lot of pests have natural enemies that can help to keep their populations down. Conservation biological control in urban areas can also help.
Preventing future bagworm infestations
- Monitor your plants: Check them regularly for signs of bagworms.
- Maintain plant health: Make sure your plants get enough water and fertilizer. Prune them regularly to keep them healthy.
- Take proactive measures: Add bagworm treatment to your gardening schedule.
The Bottom Line
When it comes to bagworms, early detection and timely action are key. If you want to keep your landscape plants healthy and beautiful, you’ll want to use an integrated pest management approach. By following these guidelines, you can effectively manage bagworms and protect your trees and shrubs.