10 Best Caterpillar Killer 2025 in the United States

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 Ortho BugClear Lawn Insect Killer is a granule-based product that targets a wide range of pests including ants, spiders, ticks, fleas, armyworms, and grubs, which includes caterpillars like armyworms that can harm your lawn. It’s designed for outdoor use and can cover a large area, up to 16,500 square feet, making it suitable for medium to large lawns. The product kills insects on contact and provides up to six months of control against most ants, which means fewer repeated treatments are needed for those pests.

Application is straightforward when used with a Scotts spreader, and watering the lawn afterward helps activate the insecticide. While it covers many pests, the product excludes some ant varieties like pharaoh, carpenter, and harvester ants from its control. The granule form is easy to apply but may require careful spreading to avoid uneven coverage. Its safety is typical for chemical lawn treatments, so following label instructions is important to protect plants and pets.

For dealing with caterpillars specifically, this product is effective and convenient, especially if you want a broad-spectrum insect killer for your lawn and garden areas.