The most successful attempts at getting rid of bagworms come from spraying organic pest control such as Bacillus thuringiensis and spinosid in May during their hatch. Chemical sprays such as acephate, bifenthrin, carbaryl, cyfluthrin, cyhalothrin, malathion, or permethrin are also very effective.
- Find last year's bag
Bagworm larvae are about one millimeter long. This makes them nearly undetectable. The best way of finding these pests is to find the bag that the adult female created last year. The larvae over-winter in that bag and will emerge in May and eat the leaves around the bag until August.
- Spray the tree with pesticide
Complete spray coverage is necessary. Every leaf and branch must be sprayed on both sides from the tip to the trunk. This is a lot of insecticide and many refills will be needed. Try organic versions such as Bacillus thuringiensis or spinosid if you are concerned with the environmental impacts of using so much chemical pesticides.
- Plant a deterrent
Planting members of the Aster family in close proximity to the infected or susceptible tree will attract ichneumonid wasps, the natural predator of bagworms. These wasps are parasites of the bagworm, by laying their eggs inside the worm's body. The wasps are harmless to humans and have no stingers.