Which type of spray kills bagworms?

Sprays with the active ingredients of acephate, carbaryl, or permethrin kill bagworms [Thyridopteryx ephemeraeformis]. A spray with the active ingredient malathion kills too. But such a powerful chemical control needn't be considered in most cases.

Reluctance likewise may be shown regarding the use of carbaryl. It's the active ingredient in 'Sevin'. It controls bagworms, but at the price of encouraging mites.

Whichever the control chosen, timely use of the product is important. The most effective treatment times are late May to mid June. That's because the bags are less than a half inch long, and vulnerable to the active ingredients.

Otherwise, Bacillus thuringiensis is an effective control. But once again, timing is everything. The best time range is mid to late June, when the larvae are still young.

Additionally, handpicking may be the control, from August to May. The bags should be bagged and burned. Otherwise, they and their eggs will over winter, and hatch in late May.