I am fairly certain that this is the cocoon of an Ichneumonid wasp in the subfamily Campopleginae. Wasps in this group are endoparasitoids, usually on moth caterpillars. This is an interesting and complex form of parasitism. I have found similar, or most likely the same cocoons all over the region on a variety of plants. Sometimes the cocoons hang by a slender but strong thread, other times they are attached like this one, along their length.