Bagworms are a common and pesky problem for many homeowners who take pride in their landscape. These caterpillars live their entire lives in tough, protective “bags” made of silk, feeding on foliage until the end of summer.
An infestation of bagworms can lead to unsightly damage to various types of trees, including arborvitae, red cedar, juniper, and spruce1.
Knowing how to treat and prevent bagworm infestations is essential to maintaining a healthy and attractive landscape.
In this article, we’ll explore all you need to know about bagworm treatment, from identifying symptoms to taking effective action against these destructive pests. Stay tuned for valuable tips on keeping your trees and plants bagworm-free.
Bag Worm Lifecycle
Eggs and Hatching
Bagworms lay their eggs in protective silk bags during the fall, which hatch in spring. Each female bagworm can lay up to 500-1,000 eggs within the bag, ensuring a large population in the next season.
Larval Stage
As the tiny caterpillars hatch, they construct their own bags using silk and nearby host plant materials. The larvae remain in these bags while they feed on the leaves of various trees such as arborvitae, red cedar, and junipers.
- Bags made of silk and plant materials
- Larvae feed on various trees’ foliage
Larvae will continue growing and feeding throughout the summer months.
Pupa and Adult Stage
By late summer, bagworms enter the pupal stage within their bags. During this stage, they undergo metamorphosis and turn into adult moths.
Males transform into fully developed moths that can fly, while females remain underdeveloped, wingless, and do not leave their bags.
Males vs. Female Adult Bagworms:
| Characteristic | Males | Females |
|---|---|---|
| Appearance | Fully developed moths | Underdeveloped, wingless |
| Movement | Can fly | Do not leave their bags |
Males will then seek out the sedentary female bagworms for mating. After mating, the female’s lifespan ends, and she lays her eggs within the bag to start a new generation of bagworms. The adult males also die shortly after mating.
Identifying Bagworms and Infestations
Bagworms on Trees and Shrubs
Bagworms are common insect pests that affect trees and shrubs, particularly evergreens like junipers and arborvitae. They create cone-shaped bags using silk and bits of host plant materials.
Here are some common plants affected by bagworms:
- Arborvitae
- Juniper
- Pine
- Spruce
- Willow
- Oak
- Locust
Visible Damage to Plants
These pests can cause defoliation and visible damage in landscape plants, including deciduous trees. Bagworms consume leaves and needles, causing trees and shrubs to lose foliage.
Signs of bagworm infestation:
- Bags hanging from twigs
- Chewed or chewed off leaves
- Thinning of foliage
- Branch dieback
Comparison Table
| Plant Type | Damage from Bagworms | Examples |
|---|---|---|
| Evergreens | Defoliation | Juniper, Arborvitae, Pine |
| Deciduous | Some leaf consumption | Oak, Locust, Willow |
Bag Worm Treatment and Control Measures
Natural Predators and Biocontrol
Bagworms can cause significant damage to trees. One effective method to control their infestation is by leveraging their natural predators. Some common predators include:
- Birds
- Small mammals
- Insectivorous insects
For example, you can attract birds to your garden by providing nesting boxes and feeders. Another biocontrol method is using Bacillus thuringiensis (Bt), a natural bacterium that targets caterpillars and minimizes damage to beneficial insects.
| Control Method | Pros | Cons |
|---|---|---|
| Natural Predators | Environmentally friendly | May not provide rapid control |
| Bacillus thuringiensis | Targets caterpillars specifically | May require multiple applications |
Hand-Picking and Removal of Infested Plants
Hand-picking is another strategy for managing bagworm infestations. This involves:
- Inspecting your trees regularly
- Removing the bags manually as soon as you notice them
Bagworms tend to overwinter as eggs inside female bags, so it’s important to remove them during their dormant period to prevent further infestations.
Chemical Treatment for Bagworms
Proper Timing for Effective Treatment
To effectively treat bagworms with chemical control, proper timing is crucial. The ideal time to treat bagworms is during summer when they are still in their young larvae stage.
Bagworm eggs typically hatch in late May or early to mid-June, making this the prime time to initiate treatment.
Recommended Insecticides
Several effective insecticides can be used for bagworm control. These include:
- Malathion
- Carbaryl
- Diazinon
- Cyfluthrin
| Insecticide | Pros | Cons |
|---|---|---|
| Malathion | Effective against bagworms | May be harmful if not used properly |
| Carbaryl | Fast acting | May be toxic to beneficial insects |
| Diazinon | Broad spectrum control | Restricted in some areas due to environmental concerns |
| Cyfluthrin | Low toxicity to mammals | Can be harmful to aquatic life |
Keep in mind that chemical control should be applied to caterpillars early in the season. Late August and early September are not ideal times for treatment, as bagworms cannot be killed by pesticides at this stage.
Always follow label directions and safety precautions while using insecticides.
Preventative Measures and Maintenance
Regular Monitoring and Inspection
To prevent bagworm infestations, regularly inspect your plants for signs of feeding or defoliation. Caterpillars hide in sealed bags made of silk, making them challenging to spot.
Monitor your plants, especially those prone to infestations (e.g., arborvitae, red cedar, juniper, and spruce) between June and August, when the larval stage of bagworms is most active.
Keep an eye for additional plants that are at risk, such as black locust, elm, persimmon, honeylocust, poplar, and hemlock.
Keeping Your Garden Clean and Healthy
- Remove debris and dead leaves to limit the hiding places for bagworms.
- Encourage birds like sparrows that feed on bagworms by placing bird feeders near infested plants.
- Regularly prune your plants to maintain a healthy environment and prevent bagworms from finding attractive breeding spots.
One effective way to manage bagworm populations is hand-picking their bags from infested plants in October when they are sealed and less mobile.
Remove any egg sacks found during this time as well, taking care not to break them to prevent the next generation from emerging. Dispose of the bags away from your garden.
For larger infestations, consider using a sprayer with horticultural dish soap or specific insecticides like Orthene. However, chemicals should be a last resort, as they can harm beneficial insects and bacteria.
Keep in mind that weather can impact the mating and development of bagworms. Droughts may result in the earlier emergence of adult bagworms, while rainy conditions can delay their mating.
During the larval stage, female bagworms are fertilized by males and produce egg sacks. Regular monitoring and removing the bags can help prevent the next generation of bagworms from emerging and causing more damage.
Bug Control Recommendation Tool
Conclusion
To summarize, bagworms are insects that belong to the family Psychidae. They have worm-like bodies and make bags from plant materials and silk.
They are found in many regions of the world, where they feed on various plants, especially evergreens.
They can cause defoliation and death of plants if left unchecked.
You can control them by hand-picking, pruning, or using biological or chemical pesticides. Bagworms are pests that need to be treated to protect the health of plants.
Footnotes
3 Comments. Leave new
Bagworm Tea!
While the baggy cocoons of Psychidae are not considered edible, I’ve read of several accounts tea made from the bags, from Mexico and Madagascar [where the larvae are consumed as well]. Beyond this, there’s documentation of the use of the cocoons as spiritual fetishes from The Congo.
Dave
http://www.smallstockfoods.com
How do I kill them before they take hold of all my Arborites?
Are harmful to the trees? Should I pull them off and dispose of them?