We saw many, many of these nests in the Choke Cherry (Prunus virginiana) shrubs along our roadsides. At first we thought they were the Eastern Tent Caterpillar, but they were driving me nuts, so we stopped the car and cut off a nest to take home and observe. They were NOT the Eastern Tent Caterpillar!!! An Internet search revealed their identity on the Forest Pests Website. To quote them: "Ugly Nest Caterpillar is a native species that is widely distributed throughout Canada and the northeastern United States. It may be abundant some years and then scarce for long periods. It is of little economic importance, except that it spins unsightly webs on its hosts and these are often noticeable along roadsides."