Butterfly watching has me attuned to caterpillars, so when I spotted this on a dogwood leaf this evening I was excited to find out which one I had discovered.
Our Peterson First Guide didn't offer a match, so I went online to search on characteristics. That got me nowhere. Then I went to 'caterpillar maine dogwood' and up popped two images from Jim McCormac's blog entry on sawflies and yellowjackets.
It's not a butterfly or a moth, it's a sawfly. bugman clued me into dogwood sawflies on What's That Bug? which itself pointed to Penn State's Susan Parker with an Integrated Pest Management perspective and a Chris Adams entry on bugguide.net. On the latter site, danielj reports that correspondent Millie's image was a first for bugguide.net. There are others there.
This squirmy thing had climbed to the tip of a pagoda dogwood, but we've got red osiers aplenty. Time to think twice about the positive first impression?
"This is an insect you can enjoy" said Dave Smitley in his alert (PDF) for Michigan State, though he makes disclaimer about the question being asked in September.
One last (?) thing: A look at an adult from Minnesota Seasons.
Another last thing: bugguide.net genus discussion mentions four species, three in the east, two of which are common: Macremphytus tarsatus and Macremphytus testaceus.