How to Get Rid of Bagworms Before They Damage Your Shrubs
You may be walking through your yard and notice small, cone-shaped bags hanging from the branches of a shrub or tree. At first glance, they can look like harmless pieces of dried foliage.
Unfortunately, those little bags are not decorations. They may be bagworms.
Bagworms are caterpillars that build protective cases using silk, leaves, and small pieces of twigs. As the caterpillars feed and grow, the bags become larger and easier to see. By the time homeowners notice a serious infestation, the insects may have already caused significant damage.
The best approach is to inspect your plants early and act before the bagworms have time to take over.
What Do Bagworms Look Like?
Bagworm cases often look like tiny pinecones or miniature ornaments hanging from branches. They are usually covered with bits of leaves and plant material, which helps them blend into the shrub or tree.
The bags may start out very small in late spring. As summer progresses, they can grow to approximately one or two inches long.
Inside each moving bag is a caterpillar. The caterpillar crawls along the plant while carrying its protective case and reaches out to feed on the foliage.
Which Shrubs and Trees Do Bagworms Attack?
Bagworms can feed on many types of landscape plants, but they are especially damaging to evergreens.
Common targets include:
- Arborvitae
- Junipers
- Cedars
- Cypress
- Pine trees
- Spruce trees
- Leyland cypress
- Some broadleaf shrubs and deciduous trees
Evergreens are especially vulnerable because they may not quickly replace damaged foliage. A heavily infested evergreen can turn brown, become thin, and struggle to recover.
Bagworms may also feed on deciduous plants such as maples and oaks. These plants often recover more easily because they can produce new leaves, but a severe infestation can still weaken them.
Why Bagworms Can Become a Big Problem
A single bag may not look like much of a threat. However, each female bagworm can produce hundreds of eggs.
The eggs remain protected inside the bag through winter. When the weather warms in late spring or early summer, the tiny caterpillars hatch and begin feeding.
Young bagworms are difficult to see because their bags are small. This allows the infestation to grow quietly until the damage becomes obvious.
If you wait until late summer, the caterpillars may be larger and more difficult to control with sprays.
Inspect Shrubs and Trees Regularly
The easiest way to control bagworms is to find them early.
Take a few minutes to inspect your shrubs and trees closely. Look for small, brown, spindle-shaped bags attached to the branches.
Pay special attention to arborvitae, junipers, cedars, and other evergreens. Check deep inside the foliage instead of only looking at the outer branches.
Bagworm cases can blend in surprisingly well. What looks like a dried leaf may actually be a hungry caterpillar carrying its own little camouflage tent.
Remove Bagworms by Hand
If you only see a few bags, hand-picking is often the simplest solution.
Wear gloves and pull each bag from the plant. Place the bags in a sealed trash bag or a container of soapy water.
Do not drop them on the ground beneath the shrub. Eggs inside the bags may still hatch and create a new infestation.
Hand-picking works especially well during fall, winter, and early spring before the eggs hatch. It can also help during summer when the plants are small enough to inspect thoroughly.
Treat Bagworms While They Are Small
If there are too many bags to remove by hand, an insecticide labeled for bagworms on ornamental plants may be needed.
Timing matters.
Treatments are most effective when the caterpillars are young and actively feeding. In many areas, this is during late spring or early summer.
Products containing Bacillus thuringiensis, commonly called Bt, may help control young caterpillars. Spinosad is another ingredient commonly used for caterpillar control.
Always read the product label carefully. Make sure the label lists the plant you are treating and follow all mixing, application, and safety directions.
Spray coverage is important because the bag protects the caterpillar. As bagworms grow larger, treatments may become less effective.
Be Careful Around Pollinators
Use extra caution when applying any insecticide near blooming plants.
Avoid spraying flowers while bees, butterflies, and other pollinators are actively visiting them. Whenever possible, use hand-picking or targeted treatment rather than spraying the entire yard.
Apply products only where needed and always follow the directions on the label.
Will Damaged Shrubs Recover?
Recovery depends on the plant and the amount of damage.
Deciduous shrubs and trees may recover if they lose some leaves because they can often produce new foliage.
Evergreens may not recover as easily. Once arborvitae, junipers, and similar plants lose large sections of foliage, the bare areas may remain thin or brown.
If the damage is severe, prune away dead branches when appropriate and continue to water the plant deeply during dry weather. Avoid heavy fertilizing during extreme summer heat because it can place additional stress on the shrub.
How to Prevent Bagworms Next Year
The best time to reduce next year’s bagworm population is before the eggs hatch.
During fall and winter, inspect your shrubs and trees for old bags. Remove and destroy every bag you can find.
A little time spent inspecting your plants during the cooler months can prevent a much bigger problem the following summer.
You should also keep your shrubs healthy by watering deeply during dry weather, adding a proper layer of mulch, and avoiding unnecessary stress.
Final Thoughts
Bagworms may be small, but they can cause serious damage if they are ignored.
Check your shrubs and trees regularly, especially evergreens such as arborvitae, junipers, cedars, and pines. Remove visible bags by hand whenever possible. If treatment is needed, act while the caterpillars are young and easier to control.
Catching the problem early is much easier than trying to rescue a badly damaged shrub later in the summer.