Question
I have a 12' arborvitae that was attacked by bagworms last summer. The top 4-5' of the tree seems to be dead w/ no new growth this spring. I was told that the Arborvitae can come back from this type of damage. Is that correct? If so what else should I do to assist in it's regrowth? Do I need to trim the dead portion back? Any help is greatly appreciated.

Answer
It is true that bagworms should not damage the tree to the point that it would die.  It is most likely something else causing the death in the top.  Scratch the bark with your fingernail and see if it is green underneath.  If so, it is alive and shoud regrow.  If not, then it is dead and should be cut off.  The only other thing is to fertilize the plant lightly and water during periods of dry weather.  This is about all that can be done provide there are no insects or diseases present.  Give the tree a closer observation and if you find anything else unusual please respond back with your opinion.  We can go from there.  Thanks.