Is it possible that mulch can contain and support bagworms? I had very healthy trees and shrubs. About one week after they were mulched, I began to notice bagworms on all of my shrubs. I have never had problems with bagworms, nor have my neighbors. I am concerned that it could be the mulch. If it is, how do I treat not only my plants but also the mulch?
Mulch and Bagworm Infestation
Certified GKH Gardening Expert
Generally, these pests do not 'live' in mulch; however, anything is possible. The best treatment for the bagworms is using an insect spray that includes permethrin. You will want to apply weekly or at least every two weeks when you have a good infestation. There is only one organic chemical treatment that can be used very early in the larvae cycle. Bacillus thuringensis (Bt) can be used right at the egg hatching time to help control. Otherwise hand pulling or power washing off the ‘bags’ off the plant is the only organic control for bagworms.
Here is an article that you may find helpful: https://www.gardeningknowhow.com/plant-problems/pests/insects/treatment-bagworms.htm