Snowberry Sphinx Moth Caterpillar (Sphinx vashti): Caterpillar identification can be difficult, but we’re pretty confident this is a snowberry sphinx moth caterpillar. They inhabit mountain woodlands and prairie stream valleys in western North America. In regard to the common name …take a wild guess as to the type of plant the caterpillars prefer. Photo by Glenn Marangelo on 8/12/18 near Clinton, MT.