This walkingstick is a member of a large group of insects, the Order Phasmida. Walkingsticks survive by mimicking plant stems and leaves, thus reducing the threat of predation by animals that eat insects. Many species have adapted body parts that resemble leaves, etc., in addition to the stick shape.
Interestingly, one tropical species of walkingstick, similar in appearance to the one in the photo, is the longest insect on record, measuring more than 22 inches.
I cannot explain the little ringlet at the posterior end of the insect.
They feed on tree leaves, and in most cases actually stimulate tree growth through what amounts to pruning. It is possible, however, for an infestation of walking sticks to actually injure a tree. This is rare and poses no threat to forests.
For those who have to know. I believe the specimen in the photo is a Northern Walkingskick, Diapheromera femorata.
Posted in response to Cee’s Oddball Photo Challenge.