Best Bt Spray For Bagworms: Eight Bt Options Compared

#1 · Best Overall

1. Monterey BT Concentrate

• Weight: 16 oz
• Form: Oil

Best for: Measured concentrate for bagworms.

Why it ranks #1: Its listed target pests explicitly include bagworms, it covers shade trees and ornamentals, and the 16-ounce concentrate includes a measuring spoon.

Bagworms are named among the target pests on Monterey BT’s label, giving this 16-ounce concentrate a specific connection to the problem in this roundup. Its included measuring spoon supports portioning the concentrate for mixing, while the listed plant range spans vegetables, shade trees, and ornamentals for broader garden use.

The concentrate format and bundled measuring spoon make this a mixing-based option rather than a ready-to-spray bottle; the spoon gives users a tool for measuring before preparing a spray. Monterey lists bagworms, gypsy moths, fall cankerworms, and other caterpillar or worm-type insects, with use across vegetables, shade trees, and ornamentals. The listing also identifies earthworms and bees as safe when used as directed, and instructs users to wash after mixing and application.

Skip it if you need a ready-to-use spray without mixing; Bonide Captain Jack's Thuricide Ready-to-Use is listed in spray form.

This Monterey concentrate suits gardeners targeting bagworms across vegetables, ornamentals, or shade trees who are comfortable preparing a spray. The measuring spoon helps with portioning, but mixing and the listed cleanup precautions are part of the workflow.

Listed on Amazon as: Monterey BT – Bacillus Thuringiensis for Organic Worm and Caterpillar Control Bundled with Measuring Spoon – Concentrate for BT Spray – 16 oz

#2 · Larger Listed Size

2. Monterey B.t. 32 oz

• Form: Oil

Best for: Larger Monterey bagworm concentrate.

Why it ranks #2: The listing specifically names bagworms and coverage for shade trees and ornamentals; the 32-ounce size is larger than the other Monterey option.

Monterey’s 32-ounce B.t. concentrate names bagworms among its target pests, pairing a specific pest claim with a larger listed bottle size than its 16-ounce counterpart. Its included spoon supports measuring for mixing, while the product’s plant list covers vegetables, shade trees, and ornamentals.

This oil-form concentrate is a mixing-based choice: the included spoon gives a measuring tool, while the 32-ounce listed size provides more product than Monterey’s 16-ounce version. Its target list includes bagworms, gypsy moths, and other caterpillar or worm-type insects, and its foliage uses extend to shade trees and ornamentals as well as vegetables. Monterey also states that earthworms and bees are safe when the product is used as directed; mixing and cleanup precautions remain part of use.

Skip it if you want a ready-to-use bottle and no mixing step; Bonide Captain Jack's Thuricide is listed as ready-to-use spray.

This larger Monterey bottle fits gardeners treating bagworms across a range of foliage and willing to mix concentrate. The included spoon supports measuring, while the label’s safety directions and cleanup steps should suit your application routine.

Listed on Amazon as: Monterey B.t. Bacillus Thuringiensis, 32 oz with Spoon

#3 · Organic Gardening

3. Fertilome Caterpillar Killer

• Weight: 12 oz
• Form: Oil

Best for: Selective organic garden caterpillar control.

Why it ranks #3: It explicitly lists bagworms, fruits, ornamentals, and shade trees, and its product details identify it as OMRI Listed for organic gardening.

OMRI listing gives ferti-lome Caterpillar Killer a clear place in organic gardening plans, while its target list specifically includes bagworms. The 16-ounce Bt spray is described as selective for harmful leaf-eating insects, making it relevant to gardeners seeking caterpillar control across vegetables, fruits, ornamentals, and shade trees.

The product’s selective-targeting claim says it is intended for harmful insects and leaves non-leaf-eating insects unharmed, a useful distinction for mixed garden plantings. Its listed uses cover vegetables, fruits, ornamentals, and shade trees, while named targets include bagworms, tomato hornworms, and gypsy moths. The OMRI-listed status supports consideration in organic gardening, and the water-soluble special feature is relevant to preparing the product for use; the supplied facts do not specify a mixing rate.

Skip it if you need a ready-to-use application method with stated leaf directions; Bonide Captain Jack's lists direct foliage application.

Choose ferti-lome for an organic-gardening plan where selective caterpillar control and a named bagworm target matter. Its listed plant range is broad, but check the product directions for the application rate and preparation details you need.

Listed on Amazon as: Fertilome (16012) Caterpillar Killer Spray with Bt OMRI Listed, 16 oz

#4 · Powder Option

4. Valent Dipel Pro DF

• Weight: 16 oz
• Form: Powder

Best for: Dry-flowable bagworm treatment.

Why it ranks #4: The description specifically includes various bagworms and ornamentals, while its dry flowable powder is described as easy to measure and mix.

DiPel PRO DF explicitly lists various bagworms among more than 30 insect species it controls, making its target breadth a key reason to consider it. The dry-flowable powder is described as dust free and easy to measure and mix, and it is OMRI listed with no time-to-harvest restrictions.

The dry-flowable formulation is described as dust free and easy to measure and mix, which supports a more controlled preparation workflow than handling an unspecified liquid concentrate. Its registration for a variety of ornamentals and its stated control of more than 30 insect species, including various bagworms and tent caterpillars, suit gardeners addressing multiple ornamental pests. The listing also says there are no time-to-harvest restrictions and identifies the product as OMRI listed; it comes as a one-pound bag.

Skip it if you want a ready-to-use bottle rather than powder preparation; Bonide Captain Jack's is listed as a ready-to-use spray.

DiPel PRO DF suits gardeners treating ornamentals for bagworms or several listed insect species who are comfortable measuring and mixing powder. Its dry-flowable format supports that workflow, but it is not a ready-to-use spray.

Listed on Amazon as: Valent USA Dipel Pro DF Biological Insecticide BT 54%, 1lb Bag

#5

5. Bonide Thuricide Concentrate

• Weight: 1.3 lb
• Form: Liquid

Best for: Harvest-timed home garden Bt.

Why it ranks #5: This liquid concentrate contains Bacillus thuringiensis and is described for caterpillar control, but the supplied details do not specifically name bagworms.

Bonide Thuricide Concentrate is described as approved for organic gardening and usable up to the day of harvest, making harvest timing its clearest differentiator. The liquid Bt concentrate is positioned for home-garden pest control, with Bacillus thuringiensis identified as its active ingredient.

The naturally occurring Bacillus thuringiensis active ingredient provides the stated basis for insect control, and the concentrate format makes this a preparation-based product rather than a ready-to-use bottle. Bonide says it can be applied up to the day of harvest and is approved for organic gardening, details that matter when coordinating treatment with garden picking. The available description begins listing moth-related control but does not establish a bagworm-specific target or provide an application rate.

Skip it if you require an expressly named bagworm target; Bonide Thuricide 8 oz lists bagworms among its caterpillar-control uses.

This Bonide concentrate fits home gardeners weighing organic-gardening status and harvest timing. Its up-to-harvest-day claim is useful for planning, but the available product facts do not specifically name bagworms, so match the target label to your pest.

Listed on Amazon as: THURICIDE BT CONC 16OZ

#6

6. Southern Ag Thuricide BT

• Weight: 9.9 oz
• Form: Liquid

Best for: Liquid Bt for caterpillar control.

Why it ranks #6: Its liquid Bt is described as a biological caterpillar control, but the supplied listing does not identify bagworms among its target pests.

Southern Ag presents Thuricide BT as a liquid biological insecticide made from a bacterium toxic to certain pests, giving gardeners a Bt-based route for caterpillar control. The 16-ounce pint format is identified as liquid, and its listed active ingredient is Bacillus thuringiensis, the same ingredient as Dipel.

The bacterial active ingredient gives the product its biological insecticide identity, while the listing describes its purpose as caterpillar control. Its liquid form distinguishes how it is supplied from dry-flowable Bt products, but the supplied facts do not give an application rate or named plant list to guide specific bagworm treatment planning. Buyers comparing it with more detailed labels should account for that limited product information before choosing it for a particular planting.

Skip it if you require a listing that names bagworms specifically; Monterey BT 16 oz identifies bagworms among its target pests.

Consider Southern Ag Thuricide if a liquid Bt caterpillar-control product is your priority and you can verify application guidance for your intended plants. The available facts do not specifically identify bagworms or provide a use rate.

Listed on Amazon as: Southern Ag Thuricide BT Caterpillar Control, 16oz – Pint

#7

7. Bonide Thuricide 8 oz

• Weight: 10.56 oz
• Form: Spray

Best for: Broad garden concentrate for bagworms.

Why it ranks #7: This ready-to-mix liquid lists caterpillars, loopers, and moths and covers shade trees and ornamentals, but does not explicitly name bagworms.

Bonide Thuricide BT Concentrate names bagworms among its caterpillar-control targets and covers an unusually broad listed range of garden plants, including nuts, fruits, vegetables, shade trees, and ornamentals. The eight-ounce ready-to-mix solution offers a compact concentrate format for gardeners planning foliage treatment across different plant types.

The liquid concentrate uses Bacillus thuringiensis to control caterpillars, loopers, cabbageworms, hornworms, and leaf rollers, with bagworms included in the listed pest information. Its plant coverage extends from almonds, apples, and grapes to vegetables, nuts, shade trees, and ornamentals, making it relevant to mixed gardens and small orchards. Because it is ready to mix rather than ready to spray, buyers should account for preparing the solution before treating their plants.

Skip it if you need a ready-to-use bottle without mixing; Bonide Captain Jack's Bacillus Thuringiensis is listed as ready-to-use spray.

This Bonide concentrate fits gardeners protecting mixed plantings, including fruit trees, nuts, vegetables, and ornamentals, from listed caterpillar pests. Choose it if mixing is acceptable; the eight-ounce format is ready to mix, not ready to spray.

Listed on Amazon as: Bonide Thuricide BT Concentrate, 8 oz Ready-to-Mix Solution for Caterpillar, Moth and Worm Control in Lawn and Garden

#8

8. Bonide Captain Jack's Bt

• Weight: 2.3 lb
• Form: Spray

Best for: Ready-to-use shade-tree spraying.

Why it ranks #8: This ready-to-use spray targets several caterpillars and covers ornamentals, but its supplied pest list does not mention bagworms.

A 32-ounce ready-to-use Bt spray gives gardeners a direct option for treating caterpillar-stage pests without starting with a concentrate. Bonide lists tent caterpillars among its targets and includes shade trees, ornamentals, fruits, and vegetables, so the product can suit mixed plantings where foliage protection is the priority.

Shake the bottle well and apply directly to the tops and undersides of leaf surfaces, a practical route for treating foliage without preparing a tank mix first. The listed ready-to-use format is paired with directions for use through a hose-end sprayer, pressurized sprayer, or mist blower, offering equipment choices for different garden sizes. Its stated targets include tent caterpillars and hornworms, and the listing says it does not harm birds, earthworms, or beneficial insects such as honeybees and ladybugs.

Skip it if you want a concentrate specifically labeled for bagworms; Monterey BT lists bagworms among its target pests.

Choose this Bonide bottle for gardeners wanting ready-to-use Bt for mixed plantings that include shade trees, vegetables, or ornamentals. Its listed directions call for shaking and treating both sides of foliage, so plan for thorough leaf coverage.

Listed on Amazon as: Bonide Captain Jack's Bacillus Thuringiensis BT, 32 oz