Bagworms disappeared?
 

Hi folks - hoping someone with some bagworm experience can maybe shed
some light on this...

We have a mid-size Arborvitae and recently discovered a substantial
infestation of bagworms. We started picking them off but realized we
might miss some and the tree was already starting to show major signs
of damage (brown areas, etc). So, I never love doing this, but did a
quick spray over the entire tree with some Sevin type insect killer.
Afterwards we could see some of the worms climbing around...possibly
trying to move their bags? Anyway, a day later, they seemed to all be
dead - no bags moving on the tree. A day or so AFTER this, we came
back to still remove the bags (so-as to remove any eggs from the
area), and it appears all the bags are now empty? There are no worms
to be found, dead or alive. I'm 'happy' about this, but also perplexed
as to where they went? I have yet to find a dead worm on the ground
near the tree. Now, i will say that we witnessed several birds that
would perch nearby and fly to the tree, snatch a worm, fly away. This
was BEFORE we sprayed. Is it possible they ate up all the worms that
may have dropped from their bags, and/or eventually died partially out
of their bags?

My biggest concern here, of course, would be that the worm population
made its way to a new host plant and I'll find this out later in the
season! Thanks for any help you can give.