The attached, linked files provide the characters and character matrix for publications describing immatures of the New World treehoppers (Membracidae, Melizoderdae, and Aetalionidae) by McKamey, Wallner, Porter, Wallace, and Phillips, or some combination thereof. Characters for each body part are assigned a number, and each character within each body part are assigned a letter, because additional characters (and states) are expected to be discovered with each newly examined tribe or subfamily and it is desirable to keep all characters pertaining to a body part together. With each publication, both of these linked files will be updated. Presently, the characters and matrix cover the tribes Amastrini and Thuridini (Smiliinae).