10 Best Caterpillar Killer 2025 in the United States

The Monterey B.t. Biological Insecticide is a liquid concentrate designed specifically for organic gardening. It utilizes Bacillus thuringiensis (B.t.) as its active ingredient, which is known for effectively targeting caterpillar and worm-type pests like cabbage loopers, bagworms, and gypsy moths. This makes it highly effective in protecting a wide range of plants, including vegetables, ornamentals, and shade trees. The formulation is organic and OMRI listed, ensuring it adheres to strict organic gardening standards, making it a suitable choice for eco-conscious gardeners.

One of its standout features is its safety profile; when used as directed, it does not harm birds, earthworms, or beneficial insects such as bees and ladybugs, thus maintaining ecological balance in your garden. The liquid form allows for easy mixing and application using various sprayers, though it requires careful adherence to label directions to ensure effectiveness and safety.

One potential drawback is the need to reapply the product following heavy rains or as new foliage emerges, which could mean more frequent applications. Additionally, while it is very effective on caterpillars, it may not address other pests that gardeners might be concerned about. The one-gallon volume offers a good supply for covering larger areas, but the 8.6-pound weight might be cumbersome for some users to handle. The Monterey B.t. Biological Insecticide excels in organic caterpillar control with a strong safety profile, although it requires diligent application and might not be a one-stop solution for all pest issues.

Bonide Captain Jack's Thuricide BT is a liquid spray designed to control caterpillars and worms in home gardens, especially suitable for organic gardening. Its active ingredient is Bacillus thuringiensis (BT), a naturally occurring bacterium that targets specific pests like cabbage loopers, hornworms, and tent caterpillars without harming beneficial insects. The product comes ready-to-use with a built-in sprayer, making it easy to apply directly to fruits, vegetables, trees, and ornamental plants.

One of its biggest benefits is that it’s safe to use even up to the day of harvest, which is great for those growing edible plants organically. It starts working quickly, usually within 2-3 days after spraying. However, because it’s a microbial insecticide, it doesn’t leave a long-lasting residual effect. This means that after heavy rain or in cases of severe infestation, you’ll need to reapply it every 5 to 7 days to keep caterpillars under control.

This product is a strong choice for home gardeners looking for a targeted, environmentally friendly caterpillar killer that’s gentle on beneficial insects and safe around food plants.

The Hi-Yield (31333) 38 Plus Turf Termite and Ornamental Insect Control is a versatile outdoor insecticide that targets a broad range of pests, including caterpillars, mosquitoes, ants, beetles, cockroaches, and spiders. One of its standout features is its flexibility in application methods; it can be readily mixed with water and applied using a tank-type or power sprayer, making it convenient for large areas or spot treatments for immediate effect.

The liquid formulation ensures it is easy to mix and apply as needed. The product’s safety profile is designed for outdoor use only, which means it is not suitable for indoor pest control. Users must follow the detailed application instructions on the label to ensure effective and safe use. Its residual effect can help maintain pest control over time, but users may need to reapply based on the specific pest and environmental conditions.

One potential drawback is that it requires careful handling and precise mixing, which might be a bit demanding for users who are not experienced with such products. Additionally, the product’s weight and size make it less convenient for those with limited storage space or mobility issues. However, if you are looking for a comprehensive solution to manage various pests in your lawn or garden, this product offers robust performance and versatility. It’s best suited for homeowners who need a reliable, long-term pest control solution for outdoor areas.