My arborvitae have bag worms on them. I have removed all of them and keep watching for any more. Is there anything I can put in
the soil to protect the bush? Why does this happen, and how can I avoid this in the future?
Certified GKH Gardening Expert
I looked at several references and didn't find any that suggested using a systemic insecticide, but rather treating with a spray in May or June. These articles should help: