Hello; Thanks for submitting your garden and landscape questions to University of Maryland Ask Extension.

See University of Maryland Extension publication    https://extension.umd.edu/resource/bagworms-trees-and-shrubs. Bagworms have stopped feeding at this point and the adult female is likely dead leaving the bagworm sack full of eggs that will hatch in May of next year. It is then that you should spray foliage with Bt (Bacillus thuringiensis). Emerging caterpillar larvae that eat foliage sprayed with Bt will kill them.  Please follow product label instructions when applying. 

You may want to hire a landscape service to help you apply Bt solution to get adequate coverage on your shrubs.

I hope I answered your concerns. Christopher

Hello; Thanks for your reply. 

My guess is that the browned foliage at the top of your arborvitae is not likely to recover. A way to know is to scratch the bark of the main stem, in the dead portion of the tree, to see if there is any (living) green tissue behind the outer bark. If there is no green tissue under the bark then that part of the tree is dead. If there is green tissue then there is a chance for recovery.

Removing the dead top of your tree can provide a way for new top growth to emerge from the healthy portion of your tree. Removing the any dead foliage/branches of your arborvitae can be done any time. 

You might want to consult specialists from the US National Arboretum for better advice. 

I hope your arborvitae will recover. Christopher