My shrubs have bagworms. I have sprayed with stuff from Lowes but would like a professional outfit to come and really spray, just in case I've missed some. I contacted Ehrlich Pest control and they advised me that they'd need an ornamental spraying license. Do you know of a company that I can call?
If the trees are too large for you to spray, then contact certified arborists as they have the tools to do the job and have a pesticide license to spray http://www.treesaregood.org/
Here is some general information. Bagworms are defoliators of evergreens and some deciduous trees. At this point if the infestation is not heavy, handpick and drop into a bucket of soapy water to kill. Do not let them lay on the ground. Monitor to see if the bagworms are moving around and feeding.
If still feeding you can spray. If the bagworms are under an inch, look for a product that contains Bacillus thuringiensis which does not harm humans and beneficial insects. (Most likely too late for this.)
If the bagworms are larger than an inch, look for a residual insecticide that lists bagworms on the label.
You will have to be vigilant next season about monitoring for this pest. Handpick during the winter before the eggs hatch in June. If need be, spray with the biological control above about mid June.