Controlling Caterpillars with Bt

Hungry caterpillars can be serious pests in the garden, but you can manage them naturally with a product known as Bt.

The name "Bt" is actually an abbreviation for a bacterium called Bacillus thuringiensis that's found in soil and acts as a natural insecticide.

Bt works by interfering with the digestive systems of caterpillars, causing them to stop eating and then die. Although Bt is poisonous for caterpillars, it's safe for animals, humans, and the environment.

Different strains of Bt control different insect larvae. Look for the type that targets caterpillars that feed on vegetables, trees, and shrubs, often sold under the brand names Dipel and Thuricide.

You may need to apply Bt more than once to fully eliminate pest populations.

UF/IFAS Sites

• Safer Insecticides for Your Florida Yard

UF/IFAS Publications

• Bt (Bacillus thuringiensis) (PDF)
• Bt (Bacillus thuringiensis), A Microbial Insecticide (PDF)
• Bt (Bacillus thuringiensis): Nature's Way to Control Caterpillars and Mosquitoes (PDF)

Also on Gardening in a Minute

• Biorational Insecticides
• Caterpillars on Ornamentals
• Hornworm Caterpillars

Other Sites

• Bacillus thuringiensis--Colorado State University Extension
• Bacillus Thuringiensis--Pesticide Management Education Program
• Bacillus thuringiensis: An Insecticidal Bacteria--Arizona Cooperative Extension
• Biological Control: Bacteria--Cornell University (NY) Department of Agriculture and Life Sciences