Question
I had found bagworm sacks on two nearby burning bushes, but never found any sacks on any of our aborvitae trees.  Are the eggs I found bagworms or some other creature?  From what I read, I thought bagworm eggs stayed in their sack until hatching.  We will remove affected aborvitae, will the Seven prevent any further damage on the other aborvitaes, or are they doomed to the same fate?  They currently look normal with only a few wilted areas.
Thank you!

Amy
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Followup To

Question -
I live in MD & have one (so far) aborvitae that looks as if it's dead.  I have found what looks like spider webs and small brown eggs on a couple of leaves.  I put the eggs into a ziplock bag & they hatched into what looked like worms or catepillars with a darker brown head and lighter body.  Since then, I have found white & brown eggs on two nearby aborvitaes.  We've had near drought conditions this summer, but the aborvitae has looked worse since it has rained.  What little creature is killing my aborvitae & what can I do about it before the other two are dead?

Answer -
Amy,
The Arbs have been attacked by bagworm. The webs are probably just spiders that are looking for insects.
Treat the plants with sevin or a light rate of horticultural oil to control the eggs and the younger caterillars.
Fertilize them to help strengthen them against the attack of these pests.
Good luck.
Ed Gulliksen

Answer
Amy,
I am not proud to say that i made a mistake. The eggs and caterpillars that you found are in fact the larvae of the arborvitae leaf miner. These insects lay their eggs on the tips of the branches and tunnel into the leaves of the arborvitae, caausing the tips and later, the whole leaf, to brown out.
Sevin will control the larvae outside of the leaf, but you will need to use a systemic insecticide once they enter the leaf. I would recommend using acephate or Orthene.
It is safe to say that the other arbs have the leafminer eggs, so I would recommend treating them all.
Good luck.
Ed Gulliksen