How to Control Bagworms

Adult bagworms are 1 inch clear-winged moths. Females lay eggs inside silken bags attached to stems and branches. Ravenous larvae emerge and eat the foliage from many kinds of trees and shrubs, then build new bags with the foliage of the host plant still attached. Pupating in September, winged males emerge several days later and mate.

Difficulty:

Moderately Challenging

Instructions

Things You'll Need

• Pheromone Traps
• Pesticides
• Bow Rakes
• Garden Shears
• Garden Rakes
• Bt

1. Look for evidence of bagworms on slender stems on the underside of the foliage. The bags hang downward and may be gray or brown in color, resembling small pinecones.

2. Rake up fallen leaves and plant debris from under shrubs and trees to prevent future bagworm infestations.

3. Cut the bags from plants using a knife or garden shears. Simply pulling the bags away will leave a thread of silk that will girdle the twig as it grows.

4. Spray with Bacillus thuringiensis, an organic control for caterpillars, in early spring. Bacillus thuringiensis (or Bt) is a bacteria and is safe to use around children and pets. There are also numerous chemical sprays available for the control of bagworms.

5. Set out pheromone traps in August to capture males as they emerge and before they can mate. Pheromone traps simulate the female hormone, luring unsuspecting males to their death before mating.

6. Spray during the dormant season (winter) with a dormant-season oil spray to head off recurring infestations. (This is a preventative measure.) Dormant oil spray smothers overwintering insect eggs without damaging plants.

Tips & Warnings

• Bagworms are found mostly east of the Rocky Mountains.

• Apply pesticides when the insects are most active to get the best control.

• Always try the least toxic method of pest control as your first step.

• Although Bt is organic and safe to use, it will kill all types of caterpillars, including butterfly larvae. Spray only the plants that are affected by the bagworms and mix only the amount of spray you will use at one time.

• If you use chemical pesticides in your garden, you will kill natural predators of bagworms.

• If you choose a chemical method of control, always wear protective clothing and safety gear, including a long-sleeved shirt, long pants, neoprene gloves, goggles and a respirator.