Bagworms on Blue Spruce: Identification, Timing, and Control

Bagworms on 20–25 ft blue spruces: larvae live in spindle-shaped bags, feeding with only head/legs protruding. Bags move. By mid-August, they attach permanently and pupate.

Control Window

• Best: Late June–early July, while larvae are small and mobile.
• After August: Bags fixed; hand-picking is only reliable method.

Insecticides (check label for bagworms & spruce)

• Carbaryl (Sevin)
• Diazinon (restricted in many areas)
• Acephate (Orthene)
• Bifenthrin (Talstar)

Application

Drench the entire canopy—inner foliage must be reached. High-pressure sprayer or professional application needed for tall trees.

Cultural

Remove and destroy bags in fall/winter to reduce next year's population.