EXTENSION CONNECTION: Stop bagworms before they hatch

Published: Thursday, April 3, 2014 at 03:00 AM.

The caterpillars feed steadily for four to 16 weeks. Once the larva has consumed enough food, it attaches its bag securely with a thick silken strand to its host plant or nearby structure. 

The bagworm seals the bag's posterior end, molts and begins pupation. The bagworm’s seven- to 10-day metamorphosis results in a moth. However, the adult female’s wings and appendages are reduced to mouthparts, legs and small eyes. She remains in a caterpillar-like state a couple of weeks and releases a pheromone that attracts the male.

The male bagworm emerges as a free-flying, lacey, black moth that lives one or two days — just enough time to mate with the female in her bag. Once mated, the female dies, mummifying around her eggs.

Controlling the population

Bagworm populations can reappear in the same areas year after year. Mechanical methods and biological insecticides are the most effective practices to control bagworms. 

Handpick them from late fall to early spring and place them in a bucket of soapy water or a sealed bag to prevent new larvae from dispersing. Applying Bacillus thuringiensis, or Bt, to the foliage is an effective means of control when applied to new spring growth. 

This bacteria stops all caterpillars' feeding, so be cautious about where it is used. Many desirable butterfly larvae can be harmed if the product lands on other larval plants.

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