I was walking under a bare tree yesterday when I noticed that there was one leaf still clinging to a branch. Then I decided it was not a leaf, but most likely the case of the larva of a bagworm moth (Psychidae). Here is the cropped shot. The case was quite high and, unfortunately, I couldn't get any closer to it with my iPhone camera.
Come spring, a caterpillar, if it survives the winter, will come out of it. Two previous posts about bagworms are here and here.