7 Best Insecticide For Bagworms | Stop Bagworms Now

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The 32-ounce Monterey B.t. concentrate represents the gold standard for organic bagworm control. This biological insecticide contains Bacillus thuringiensis var. kurstaki, a naturally occurring soil bacterium that produces a protein toxin fatal to young caterpillars after ingestion. Because bagworms are susceptible to B.t. only during their early larval stage before they seal their bags, this product is the ideal first-line defense when applied at the first sign of hatch in late spring.

The included measuring spoon simplifies mixing, and the concentrate treats a substantial area — the label lists bagworm, gypsy moth, fall cankerworm, and elm spanworm as target pests. Users consistently report seeing dead caterpillars on treated foliage within two to three days, and the formulation is gentle enough to use on vegetables, ornamentals, shade trees, and fruiting plants alike. Its OMRI listing ensures compliance with organic gardening standards under the USDA National Organic Program.

For homeowners managing multiple trees or a large landscape, the 32-ounce size offers the lowest per-application cost among biological options. The product mixes instantly with water and works best with a pressure tank sprayer for reaching the upper canopy where bagworm feeding is concentrated. Reapplication every 7 to 10 days during peak hatch season is recommended for full coverage as new larvae emerge.

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Ortho Bug B Gon is a broad-spectrum synthetic insecticide that delivers immediate knockdown of bagworms on contact, making it a strong option when an infestation is already visible and growing. The ready-to-spray hose-end bottle covers up to 5,300 square feet and attaches directly to your garden hose, eliminating the need for mixing or carrying heavy sprayers. Its active ingredients, bifenthrin (0.3%) and zeta-cypermethrin (0.07%), provide residual protection on treated foliage for up to six months against spiders and several weeks against other listed insects.

Where this product separates itself is convenience for tall trees. With a standard hose, the spray reaches a significant height, and the formula is rainfast in about an hour — critical for spring applications when afternoon showers are unpredictable. Verified users report a dramatic reduction in mosquitoes, flies, and Japanese beetles after a single treatment, and many long-term users rely on just two applications per year: one in spring and one in late fall.

The trade-off is ecological impact. Both bifenthrin and zeta-cypermethrin are highly toxic to bees, butterflies, fish, and aquatic invertebrates. Ortho’s label explicitly warns against spraying open blooms or allowing drift onto flowering plants visited by pollinators. For bagworm control on ornamental trees away from flowering understory plants, this product is exceptionally effective, but it should be used as a targeted salvage treatment rather than a blanket preventive spray.

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Hi-Yield 38 Plus is a 38% permethrin concentrate — the highest permethrin percentage the EPA allows in a residential product — designed for heavy-duty, long-residual pest control on lawns, ornamentals, and trees. Permethrin works by disrupting the nervous system of insects on contact, and at this concentration, a small amount goes a long way. The label specifically lists bagworms among the pests it controls on ornamental trees and shrubs, alongside borers, bark beetles, and aphids, with residual control for up to four weeks on treated foliage — useful for bagworms that emerge over a staggered hatching window.

This product is the strongest chemical option in this lineup for mature bagworm suppression. While no contact spray can reach larvae that have already sealed themselves inside their bags, permethrin’s staying power on foliage means that newly hatched larvae that emerge days after the initial spray will still encounter a lethal dose. The label directs users to apply while larvae are young and before they’ve built their bags, then reapply at labeled intervals through the hatch window for season-long suppression.

The downside is the chemical odor, which multiple reviewers describe as similar to paint thinner — strong enough that indoor use is not recommended, and the label restricts it to outdoor use only. The formulation also contains petroleum distillates, which can stain clothing and synthetic materials. For outdoor bagworm applications on trees far from living areas, the odor dissipates quickly, but users sensitive to strong chemical smells may prefer a biological alternative for smaller jobs.

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BioAdvanced Tree & Shrub Insect Killer Ready-to-Spray uses cyfluthrin (0.75%) as its active ingredient — a synthetic pyrethroid that kills on contact and leaves a residual film on treated foliage, rather than a root-absorbed systemic. Bagworm is explicitly named on the EPA label’s registered pest list, alongside gypsy moth larvae, caterpillars, and dozens of other foliage-feeding and crawling insects. Any bagworm larva that contacts or feeds on treated leaves is exposed to a lethal dose.

The ready-to-spray formulation connects directly to a garden hose and is rainproof within one hour, a meaningful advantage for spring applications during unpredictable weather. Users report noticeable improvement in their dogwood, red maple, and ornamental tree health within days, with leaves regaining full color and no sign of the pest returning. The formula continues killing listed insects on treated foliage for up to two weeks per application.

The major caveat is standard for this class of chemistry: like other pyrethroids, cyfluthrin is highly toxic to bees and aquatic life on direct contact, and the label warns against spraying open blooms or allowing drift onto flowering plants visited by pollinators. For non-flowering evergreens like spruce, juniper, and arborvitae — common bagworm targets — this is less of a concern. For any tree that blooms, apply only after flowering has finished and avoid spraying open blossoms altogether.

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This 8-ounce bottle of Southern Ag Thuricide is the entry-level biological option for homeowners with a small number of trees or a limited area to treat. It uses the same Bacillus thuringiensis active ingredient family as our top pick, with low toxicity to humans and pets, and label directions covering use on vegetables, citrus, nuts, shrubs, trees, and ornamentals. The smaller size is ideal for gardeners who want to test B.t. before committing to a larger volume or who only need enough for a single season of spot treatments on a few trees.

Mixing is straightforward at a labeled rate of 2 to 4 teaspoons per gallon of water. Because it targets only actively feeding caterpillars, it has no effect on birds, earthworms, or beneficial insects such as honeybees and ladybugs when used as directed. It mixes instantly and is compatible with trigger sprayers, making it an easy choice for precise spot sprays on young bagworm clusters.

The trade-off is the higher per-ounce cost compared to the 32-ounce bottle of our top pick. Additionally, because B.t. degrades in sunlight, users managing a long hatch window will need multiple applications, which the 8-ounce bottle may not cover across an entire season if applied broadly.

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Bonide Eight Insect Control uses permethrin (0.125%), a synthetic pyrethroid, to deliver both fast contact knockdown and up to four weeks of residual control against a broad range of insects. Bagworms are explicitly named on the EPA label’s tree and shrub use section, alongside aphids and other foliage feeders on species like azalea, birch, and other ornamentals. The concentrated 32-ounce bottle mixes to produce many gallons of spray solution for lawns, trees, shrubs, and vegetables.

This product is especially useful when you have identified bagworm clusters on specific branches and want a treatment that keeps working after it dries. Reviewers use it effectively on aphids, beetles, and other listed pests on ornamentals, roses, and fruit trees. Because it leaves a residual film on foliage, newly hatched larvae that emerge after the initial spray also pick up a lethal dose, unlike faster-breaking-down botanical options.

Because it’s a synthetic pyrethroid rather than a botanical extract, it persists longer in the environment and carries the same precautions as other pyrethroids: avoid spraying open blooms or allowing drift onto flowering plants visited by pollinators, and keep it away from ponds and waterways. For bagworm control on ornamental trees away from flowering understory plants, this product is a reliable, budget-friendly option.

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Ferti-lome’s Spinosad Bagworm, Tent Caterpillar & Chewing Insect Control is, as the name states, labeled by name for bagworms — the product’s own label lists bagworms, tent caterpillars, armyworms, sod webworms, loopers, and other chewing insects on lawns, ornamental trees, shrubs, and flowers. Its active ingredient, spinosad, is derived from a soil bacterium and is approved for organic gardening use (OMRI listed). It works by ingestion and contact, attacking the insect’s nervous system and typically causing death within a day or two — faster than B.t.

The ready-to-spray quart bottle connects to a garden hose for easy coverage of taller trees and shrubs. Spinosad also controls leafminers, borers, leafrollers, thrips, and Colorado potato beetle on vegetables, fruits, and citrus, making it a versatile choice for gardeners who want one product that covers both ornamental and edible plantings.

The label recommends applying while larvae are young, and reapplying as needed if new hatching is observed, since — like every other contact or ingestion product in this guide — it will not penetrate a bagworm that has already sealed itself inside its bag. Spinosad is more toxic to bees while wet, so the label advises applying in the evening after bees have stopped foraging.