We've been inundated with winter moth caterpillars here lately. They are little inchworm type critters, about 1/2 an inch long, and they are decimating the leaves on many trees. The big, healthy trees will survive, at least this summer, but the weaker ones will be culled, and so goes the circle of life.
On the other hand, somebody's got to eat some of those caterpillars. And I just saw a cardinal that was doing his darndest to get as many caterpillars as he could. His mouth was just stuffed full, and he kept trying to grab more. I suppose he's got a clutch of babies somewhere to feed. Maybe I'll poke around and see if I can find the nest. The birds can take as many of those caterpillars as they want - I like green leaves.