How to Use Bt Pesticide as an Organic Pest Control

Learn how to use Bt pesticide to kill cabbage worms, tomato hornworms and other pests in your organic vegetable garden.

| April 24, 2013

Bt Pesticide

Bt is one of the safest natural pesticides you can use to control caterpillar pests without harming beneficial insects.

Photo Courtesy Safe Brand

This article is part of our Organic Pest Control Series, which includes articles on attracting beneficial insects, controlling specific garden pests, and using organic pesticides.

What Is Bt?

Bacillus thuringiensis, often abbreviated as Bt, is a naturally-occurring bacteria that makes pests sick when they eat it. There are two strains commonly used as natural pesticides.

Bacillus thuringiensis kurstaki (Btk) gives excellent control of leaf-eating caterpillars such as cabbage worms and tomato hornworms, but has no activity against insects that do not eat treated leaves. After the insects eat the bacteria, their guts rupture and they die. Bt is therefore one of the safest natural pesticides you can use in terms of controlling caterpillar pests of vegetables or fruits without harming beneficial insects.

Bacillus thuringiensis israelensis (Bti) can be useful in controlling fungus gnats in greenhouses or houseplants, or for preventing mosquito problems in standing water that cannot be drained or controlled with fish.

7/13/2017 10:49:47 PM

You are a sadistic and a sad, sad man! You do know that the Monarch LOVES milkweed, right? So, IF you didn't want Monarch caterpillars in your yard why in heavens name would you plant it? Do you know why many of us rarely see a Monarch butterfly anymore? It is because people like you plant milkweed in their yard then spray it with chemicals, so it kills the caterpillars! And you are even more sadistic, because TX is in their migration route. UGH!!!

7/2/2017 7:39:41 PM

Bt rocks when it comes to killing Monarch caterpillars. It's completely non-selective. It doesn't care what kind of caterpillar is ingesting it. It is quick and efficient when milkweed has been treated with Bt.

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