The introduction of 4 Chrysomya Robineau-Desvoidy spp. to the Americas has made obsolete previously published keys to Nearctic calliphorid larvae, particularly those covering the subfamily Chrysomyinae. To assist forensic entomologists, ecologists, and public health workers, we provide a key to 3rd instars of 8 chrysomyine species reported from or likely to occur in carrion within the continental United States. The rare (in the United States) species Cochliomyia aldrichi Del Ponte, C. minima Shannon, and Chloroprocta idioidea (Robineau-Desvoidy) are not included because specimens and suitable descriptions were unavailable.