Bagworm Control on Blue Atlas Cedar: Spot Treatment and Sanitation

Spot Spraying vs. Full Canopy Coverage

On Blue Atlas cedar (Cedrus atlantica 'Glauca'), spot-spraying visible bags is effective for light infestations. Caterpillars must feed to ingest insecticide—spraying bags directly works if coverage is thorough.

Disposal of Hand-Picked Bags

• Trash can: OK if collected weekly (caterpillars can't escape sealed bag).
• Better: seal in plastic zip-top bag → sun/heat kills quickly.
• Don't compost—may survive.

Insecticide Options

• Bt (Bacillus thuringiensis): Best for young larvae, bee-safe.
• Spinosad: Good efficacy, lower toxicity.
• Carbaryl, pyrethroids: Broad-spectrum, harm beneficials.
• Systemic (imidacloprid soil drench): Season-long, but 2-3 week uptake delay.

Prevention Focus

• Spraying reduces current population → fewer moths → fewer eggs next year.
• Doesn't prevent reinfestation from neighbors.
• Annual scouting (June) catches infestations early.

Blue Atlas Specifics

This cultivar is bagworm-preferred. Monitor annually. Early Bt treatment (June) on reachable foliage + systemic for upper canopy = best integrated approach.