Answer: Bagworms are the caterpillar stages of moths. In our area the bagworms hatch the first week of June. After they hatch bagworms spin the "bag" around themselves. They move about on the plant carrying the bag with them. The bags are made of silk, needle fragments and leaves. The bag enlarges throughout the summer as the bagworm grows, reaching a length of 1-2 inches.
The easiest method to control the bagworms is to hand pick or clip off the bags from the plants during the winter or early spring before the eggs hatch. I pick the bagworms off whenever I see them on a plant, no matter what the time of year. The bags should be destroyed by crushing or putting them in soapy water. When the infestation is too heavy for hand picking a biological control such as BT spray can be used. BT (Bacillus thuringiensis) is a type of bacteria that only kills certain insects and does not affect humans or animals. It works well only on young bagworms and must be applied in your growing region between June 15th and July 15th to be effective.
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