Bacillus thuringiensis is an effective biological control against caterpillars.
A common problem in the summer garden is the presence of pesky caterpillars and moth larvae, such as leaf rollers, cabbage loopers and tent caterpillars. Nothing is more disappointing than cutting into your fresh head of cabbage to find it destroyed by caterpillars, or having your young corn plants munched by loopers. To remedy the problem, consider an organic caterpillar pesticide that is not toxic to humans, plants or animals. In fact, it is safe enough to be applied right up until the day before harvest.
The product is Bacillus thuringiensis or BT, an effective biological control against all caterpillars. During spore production, BT produces crystals on the plant that act as a poison on the insect eating the treated plant, paralyzing the pest and killing it.
BT is sold as a liquid concentrate, which is then mixed with water and sprayed onto infected plants. This product is not caterpillar specific and will harm all caterpillars if it is digested, so it is important not to over-spray; apply it only around caterpillars you have determined to be pests. If possible, try to handpick any caterpillars from your garden or fruit trees. However, as any gardener knows, caterpillars do sometimes get out of hand and you may need to turn to a product such as BT.
Fortunately, BT is reasonably priced, safe, easy to use and can be found at any garden centre. Be sure to follow directions and apply only to infected areas. Loopers are olive-green caterpillars up to 3 cm (1.2 in.) long. They are a common problem for cabbage, broccoli, cauliflower, kale, radish, corn and turnips. They arrive in your garden via white or pale-yellow butterflies, which lay eggs that later develop into caterpillars.