Army worms and other caterpillar pests can threaten vegetable beds and ornamental plants. The following Bacillus thuringiensis (Bt) sprays are widely used for organic control, targeting caterpillars while sparing beneficial insects when used as directed. The products below are selected for compatibility with home gardens and sprayer applications, making it easier to protect crops without harsh chemicals.
| Product | Brand | Size | Form | Notes |
|---|---|---|---|---|
| Monterey B.t. Bundled with Measuring Spoon – Caterpillar & Worm Killer Organic Gardening – 8 oz | Monterey | 8 oz | Liquid concentrate | Includes measuring spoon; suitable for sprayers |
| Monterey BT – Ready to Spray Bacillus Thuringiensis – 31 oz | Monterey | 31 oz | Ready-to-spray | Organic gardening approved |
| Monterey BT – Bacillus Thuringiensis – 16 oz Concentrate for BT Spray | Monterey | 16 oz | Concentrate | Designed for sprayer dilution |
| Monterey B.t. Bundled with Measuring Spoon – 32 oz | Monterey | 32 oz | Liquid concentrate | Extended-volume option |
| Monterey B.t. Bundled with Measuring Spoon – 8 oz (second mention) | Monterey | 8 oz | Liquid concentrate | Compact size with measuring spoon |
Monterey B.t. Bundle With Measuring Spoon — 8 Oz

Monterey B.t. is a targeted insecticide that uses Bacillus thuringiensis to control caterpillars and worm-type pests. It’s designed for a wide range of plants, including broccoli, cabbage, lettuce, and tomatoes, making it versatile for vegetable gardens and ornamentals. The formulation is safe for earthworms and beneficial insects like honeybees and ladybugs when used as directed, helping maintain ecological balance in home landscapes.
Monterey BT — Ready To Spray (31 Oz)

This ready-to-spray Bt formulation is designed for organic gardening. It targets caterpillars and worm-type insects, including cabbage looper and gypsy moth, while posing no risk to birds, earthworms, or beneficial insects such as bees and ladybugs when used correctly. It’s compatible with a variety of crops and ornamentals, making it a convenient option for quick applications via sprayers or handheld sprayers.
Monterey BT — 16 Oz Concentrate for BT Spray

This Bt concentrate is formulated for organic pest control, focusing on caterpillars and worm-type insects. It protects a broad range of plants, from leafy greens to fruiting crops, while remaining safe for earthworms and beneficial insects when applied per label. Dilution guidance helps ensure effective coverage and minimal environmental impact.
Monterey B.t. Bundle With Measuring Spoon — 32 Oz

A larger Bt spray option, this 32 oz bundle provides extended coverage for bigger gardens. It targets caterpillars and worm pests across a variety of crops and ornamentals. As with other Bt products, it’s safe for earthworms and beneficial insects when used as directed, supporting integrated pest management goals in home landscapes.
Monterey B.t. Bundle With Measuring Spoon — 8 Oz (Second)

This compact 8 oz Bt bundle is ideal for small plots or as a supplementary spray option for ongoing monitoring. It supports precise application via sprayers and aligns with organic gardening standards, focusing on caterpillar and worm pest suppression without harming pollinators when used properly.
Buying Guide
Choosing the right Bt spray for army worms involves evaluating pest pressure, crop type, and garden size. Consider the following points to make an informed decision:
- Pest target and timing: Bt products are most effective when caterpillars and worm pests are actively feeding. Apply at the first sign of damage for best results.
- Formulation and dilution: Ready-to-spray products save time, while concentrates may reduce cost per application. Always follow label dilution instructions to ensure efficacy and safety.
- Plant compatibility: Most Bt products are safe for leafy greens, fruiting vegetables, and ornamentals. Confirm any crop-specific guidance on the label.
- Non-target effects: Bt is targeted and generally safe for bees and earthworms when used as directed, but avoid spraying during bloom if possible to minimize potential disruption to pollinators.
- Sprayer compatibility: Look for packaging that includes a measuring spoon or clear mixing instructions. Ensure your sprayer is compatible with the liquid or concentrate format.
- Storage and stability: Store in a cool, dry place away from direct sunlight. Use within the product’s shelf life and seal tightly after each use.
- Organic certification: If you require OMRI-listed products, verify the label confirms organic gardening approval to align with your garden standards.
- Resistance management: Rotate Bt formulations with other non-overlapping pest control methods to minimize resistance development in pest populations.
Overall, Bt-based sprays offer a targeted, eco-friendly option for managing army worms and similar caterpillars in American gardens. They are compatible with organic practices, support pollinators when applied correctly, and provide a range of packaging options to fit different garden sizes and application needs.