While no significant differences in rates of larval growth were observed among the three types of colonies, durations of the larval stage were longer for larvae fed on tissues from rabbits receiving amitriptyline than for those in the control colony. Larval mortality was measured at 5.5 percent for the control colony, but ranged from 40.5 percent to 57.5 percent for larvae in the test colonies. Durations of the puparial stage were significantly longer for larvae feeding on tissue from rabbits that had received higher doses of amitriptyline than for the control colony and the colony exposed to the lower drug dosage. These differences in the durations of the larval and pupal stages were sufficient to alter the estimation of a postmortem interval by up to 77 hours, when calculations were based on normal developmental patterns for this species at 26 degrees C. The authors note that analyses for estimation of postmortem intervals must take into consideration arthropod developmental rates, particularly where drugs may be a factor. 1 table, 1 figure, and 13 references