HI, this is my first post, but as an arborist I can't help but comment. It sounds to me like what your talking about (and what you posted a picture of) is actually called an Eastern Tent Caterpillar. They don't eat the leaves of trees but defoliate them by eating the petiole (base of leaf stock). Most trees will recover and refoliate the next growing season.
Here is a link to some more info, or just google tent caterpillar
http://www.uky.edu/Ag/Entomology/ent...rees/ef423.htm