Insect and Spider Identification: Weird bug found on my redbud tree in NJ, 1 by jspicker

jspicker wrote:
I captured this bug from one of my redbud trees today, the one with reddish leaves that isn't doing very well. The other one, with green leaves, is right next to it and even touches branches but is doing fine. The body of this bug is about 3/8" long, plus antennae and legs, one of which seems to have broken off since I captured the bug. It is in a ziplock bag because I did not want it to escape in my house or even outside if it's hurting my tree. Any idea what it is and what effect it's having on my redbud tree?