You might be able to bring photos and a securely wrapped branch (or even just a few leaves) to your county extension service for diagnosis. My personal opinion is that the most efficient way to deal with plant problems, and so the most often recommended by commercial garden services, are the most toxic, broad-spectrum treatments. These are typically not sensitive to timing, which allows the applicator to spread out his peak season, and not particularly narrowly targeted, which allows him to skip the guesswork and just "treat for everything". I'm sure there are garden service companies that are exceptions, and I hope you find one, but in my experience most of them take the same approach.

I didn't really thing it was the maple bugs, but I thought I should ask as they OWN this place. Thanks much for the earwig advice! I saw nothing out there at night (earlyish) but I tried the usual tuna-can liquid trap and the results were a resounding YECCCH! I also shot down some diatomaceous earth, since I had it kicking around. There is a repulsive picture of the culprits now on the photo album on my page. Not much there but this because I just created it so I could put a photo with my initial post. Those little things look like young earwigs to me.

So even though this is turning into more of a blog than a forum discussion, I thought I'd provide some updates. I was searching the internet for American Hornbeam pests when I found a forum discussion about Brown Marmorated Stink Bugs on another website. Suddenly I remembered that I have had dozens of them over-wintering in my bonsai room, though until recently I haven't gone to much trouble to get rid of them because they didn't appear to be doing any harm to my resident tropicals. Over the past few months though I have reduced their numbers to the point that I only see 1 every other day or so, so there are very few (if any) left at this point. Here is a dead one that I fished out of my humidity tray just a few minutes ago. These insects have antennas, but this one soaked in the water long enough that they have folded down to where you cannot see them. Has anyone had trouble with these insects eating or damaging bonsai leaves in the past? Does anyone know if they are potential bonsai pests? I read online that they could potentially cause damage to houseplants, but no specifics were provided. Also, while searching the tree again for pests, I stumbled upon what looks to be a scale infestation of the bark (only at canopy height, none found lower). I have dealt with scale on Ficus leaves before, but have never seen scale on bark/hardwood. Is this possible? I have posted pictures of what I believe to be scale below, as well as videos of me removing the scale (in hopes that someone can view them and confirm that this is indeed scale). I've also posted pictures of the marking left on the bark following scale removal, and some close ups of the scales following removal. The last picture is a close up (via microscope) of the yellow puss-looking inhabitant found under these shells. Though I am pretty sure that this is scale, I'd really appreciate if someone could confirm! Also, what pesticides are safe to use on Hornbeams? I realize that the safest thing to do is to scrape them all off, but I have little confidence that I can find them all (there are A LOT).

There's a good chance instead of butterfly, you had a sawfly larvae infestation. They can strip the foliage in very little time and since the same color as the leaf and very small, can go unnoticed until too late. My neighbor and I have both lost foliage so quickly (almost overnight) she was blaming deer - it was sawfly larvae. http://www.ppdl.purdue.edu/ppdl/weeklypics/weekly_picture5-6-02-1.html