What's infesting my redtwig dogwood?

The leaves of a redtwig dogwood started showing small holes, and now some of the leaves are totally eaten out and dead. They're littered with the bodies of very small white winged insects. The undersides of a few leaves are covered with worms (larvae?), many of them lying flat in adjacent perfect little 1/4-inch spirals that would be a nice pattern if they weren't a nasty moist pale gray with a mildewy look. Some of them are stretching out and wriggling, though. Very high yuk factor.
1. What is this? 2. What kind of measures should I take to get rid of them? (I'd prefer not to spray.) If I just cut off the branches with the larvae, will the plant have the same problem next year? (I live in E. Central Illinois, so we're sure to have some good freezes.) 3. Have the insects finished their life cycle for this year, or will there be more waves of them laying their eggs? 4. Will this infestation ultimately destroy the redtwig, or will it just play itself out this year, even if I do nothing beyond cutting off the infested branches? 5. There's an aggressive gourd plant next to the dogwood (planted itself from a decorative gourd from last Halloween), and somehow the flying insects seem to belong there. I've lots of other redtwigs, but this is the first I've ever seen this kind of infestation.
Thanks, helco
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I do not have your answer however here is some info.
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Many tree problems are associated with the following: They are Case
Sensitive.
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helco wrote:

I emailed the extension service and just received the following reply:
"Based on your description, the insect is the dogwood sawfly. Use carbaryl to control them. Continued defoliation increases the risk of canker and the red twig dogwood is already a highly canker prone plant."
Here's a site with a good photo: http://woodypests.cas.psu.edu/FactSheets/InsectFactSheets/html/DogwoodSawfly.html
There's only one generation per year, and since most leaves are not affected I'll just remove infested leaves/branches and hope they won't be worse next year. If necessary I'll remove the whole shrub. I got it very cheap: I'd stuck some bare branches in a planter for winter interest, and they rooted.
helco
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