Larvae of Phormia regina (Meigen), Phaenicia sp., and Sarcophaga sp. were identified from raccoon carcasses placed in sunlit and shaded areas at a southwestern West Virginia site in May of 2000. Samples of larvae were taken from each carcass at 3-h intervals over a 153-h experimental period. Phormia regina was clearly the dominant species with large numbers of third instars observed at every 3-h collection period from 81 to 153 h on both carcasses. Mean lengths of third-instar P. regina larvae collected from the sunlit carcass were significantly greater than mean lengths of larvae collected from the shaded carcass. Third-instar Phaenicia sp. also appeared at 81 h on both carcasses, but relatively few (≤4) individuals were present in each 3-h collection sample from 81 through 126 h. Larvae of this species were not present in samples from either carcass in those 3-h intervals from 129 to 147 h. Sarcophaga sp. larvae were also collected, but only in samples taken from the sunlit carcass at 81 and 93 h. Ambient temperatures were recorded throughout the experimental period, whereas maggot mass temperatures were not recorded until the appearance of large numbers of second instars at 48 h. From 48 to 69 h, maggot mass temperatures were equivalent to ambient temperatures; but after 69 h, maggot mass temperatures were considerably elevated over ambient temperatures.