That kudzu bug looks like a problem. I hope it doesn't make it up here. I also hope we have whopper of winter this year to kill this kind of crap off.
Ed,
I don't think the wasps are eating the leaves of your trees. They are predators. They don't eat plant material, although they do scrape wood off of old fences and other exposed wood (and sometimes plant stems) to make the "paper" that forms their nests. If you have that many of them, you've probably got a growing nest of them in your immediate vicinity (locate it ASAP --look under eaves and fence corners, etc.)
I have plenty of them around here. I consider them valuable, since I've seen them attack and consume caterpillars and even hunt scale on trees. I don't bother them (unless there is a nest in a location I pass every day-then I kill the nest off. Getting stung multiple times is no fun ;-)
Every year they scrape the surfaces off of fences and other exposed wood in my backyard, especially after rain softens it up for them. I've occasionally had them do that to deadwood on bonsai, but only on deciduous trees. Pine deadwood is, apparently, too tough for them.