These procedures present particular difficulties when performed on remains in an advanced stage of decomposition. Malathion poisoning was suspected in a case in which the remains were in an advanced stage of decomposition and the presence of malathion was confirmed by analyses of gastric content and body fat. Two species of fly larvae, Chrysomya megacephala (Fabricius) and Chrysomya rufifacies (Macquart), were present on the remains. A sample of these larvae was analyzed for malathion content. A total of 574 mg of malathion was detected in 0.26 g of pooled larvae, or a level corresponding to 2050 mg/g of larvae. Presence of organophosphates in arthropod larvae has not been documented previously and the analysis of larvae from decomposing remains may prove a useful technique for detection of these toxicants in decomposing remains. (Author abstract)