Although the katydid is in the same family as long-horned grasshoppers, they are more closely related to crickets. These pretty green bugs that look a lot like tree leaves actually do live high up on the top of trees. They lay their eggs in the crevices of the tree bark and on stems and there they overwinter until they hatch in the spring. The adults and young feast on the leaves and they will begin their calling in July. It's been described as "katy-did, she-did" and that is how they got their name. They will die when the frosts come in October and November after laying their eggs to begin another cycle. They will live their whole lives in that one tree.
This particular Katydid was hanging out on my front door. It does amaze me how many critters I find on my door. I guess it's a safe place to park for the night. I'm going to have to come up with some kind of front door special guest!