When treating with sprays, using Bacillus thuringiensis (Bt) early on small larvae works well. Once bags are big and closed they’re far harder to reach.
Don’t risk climbing without gear. Consider hiring a professional arborist if you’re more than a ladder length away.
@BagBusterBea I had fewer problems after starting regular inspections every spring. Catching the first few bags before they balloon to other trees helps a lot.
Bag-worms (bag moth larvae) are infamous for attacking arborvitae, junipers and other conifers, but deciduous trees like maples or willow aren’t safe either.
Clean up leaf litter, maintain good spacing between trees and shrubs, and avoid dense shade. All those factors reduce habitat for bag moths to thrive.
If you go the insecticide route, always follow label instructions and make sure the product is meant for bag moths/larvae, timing and coverage are important.
Controlling these pests takes a combination approach, inspect early, hand-remove when possible, apply treatment if needed, and keep monitoring. Don’t assume one method alone handles it.