Getting the ant to clamp onto the underside of a branch or leaf and then stay there until it dies is a bit harder to explain. However I am also inclined to believe there is a localized mechanism at play, such as locating the jaw actuation through connective tissue RNA. Even so, there must be some basic signaling and state detection at play. It's probably the biological equivalent of a music box that just plays the notes it's been fixed to play, but still interesting.