In this study, we asked whether different predatory assemblages (i.e., flying invertebrates, crawling invertebrates, and birds, representing vertebrate predators) in a temperate forest impose significantly different levels of predation on larvae of Orgyia leucostigma (J. E. Smith), the whitemarked tussock moth and also whether the size of whitemarked tussock moth larvae influence invertebrate and vertebrate predation. Predation by species in vertebrate and invertebrate predator assemblages on two sizes of O. leucostigma larvae on box elder, Acer negundo (L.) (Sapindales: Aceraceae) was compared using exclusion cages. Cages covered with mesh of different sizes and sticky barriers were used to exclude different kinds of predators (i.e., birds, flying invertebrates, and crawling invertebrates). Five small and five large larvae were placed on box elder saplings. Predation by birds was the greatest source of mortality of large larvae when compared with that caused by flying and crawling invertebrates. Predation played an insignificant role in the disappearance of small larvae whose disappearance was associated with their dispersal behavior.