I seem to have an infestation of bagworms on one of a series of Emerald Green Arbovitae 'Smaragd.' They have decimated the top 5' of one tree and are found over the entire tree 15' tree as well. Is there any environmentally friendly way to get rid of them of control them?
There are good non-toxic ways to control this pest, which includes hand removal of as many as you can reach, and sprays of non-toxic Bt or Spinosad. Bt only works on young worms so time is of the essence. Spinosad is newer and may have a longer period of action.
Given the size of your trees we'd think you will need to hire a tree company with the appropriate equipment to do these cover sprays.
Here is our page about them:
and more here: https://www.pennlive.com/gardening/2012/08/bagworms_are_killing_an_arborv.html