Chrysomya rufifacies (Macquart) and Chrysomya megacephala (Fabricius) are among the first colonizers of a carcass from the family Calliphoridae in the state of Florida. Chrysomya has displaced native species and thuse are important in forensic cases. Species were needed for laboratory colonies to conduct research on their behavior and compare developmental times. Developmental time from egg to adult for individuals reared on a diet of decaying chicken thighs at 28°C ranged from 17 to 20 d for Chrysomya rufifacies and 20 to 23 d for Chrysomya megacephala with the larval stage observed to last 8 to 10 d and 7 to 9 d, respectively. Adult emergence was observed at 80% for Chrysomya rufifacies with females accounting for 78% of emergent adults. Chrysomya megacephala sustained adult emergence of just 37.5% with females accounting for only 35.5%. Chrysomya rufifacies are known obligatory predators as larvae but previous colonization attempts without inclusion of other fly larvae for them to feed on have been unsuccessful. However, our colony has been reared on decaying chicken alone, with a protein source added to the adult diet for egg production. The information presented here provides insight into the behavior of Chrysomya rufifacies and Chrysomya megacephala associated with decomposing carcasses.