It is easy to understand why anyone encountering this odd katydid would not recognize it as related to the usual green, leaf-shaped insects found in trees. Bruner shieldback (Pediodectes bruneri) is a common but rarely seen creature that lives here in central Texas. One of several shieldback species (but this is the only one with a distinctive black and white mask on its face), I usually find them near areas that are lit at night. When fully grown they can be over an inch long, not including the curved sword-like ovipositor of the female. Although they are wingless, these katydids do sometimes climb up walls and on trees, and they can jump surprisingly far for such heavy insects.
Very little is published about Bruner shieldback, and it is not known just what they eat. Some terrestrial katydids are predatory, their large jaws being admirable weapons. Because I find these critters near bright areas, where many other insects tend to gather, I would guess that they are at least scavengers if not outright predators. They are less numerous than some of the herbivorous katydids, which are green and winged, but come to lights far more often. I've also found them crawling around in sheds and near buildings, places where there is not much foliage to munch on.