There is an urgent need to use environmentally safe pesticides, which do not sneak into human food or animals and then back at him and damage the environment. The photosensitizers, such like hematoporphyrin dihydrochloride (HpD), a nontoxic chemical has an ability to harm the target pest when mixed with suitable baits. When exposed to light, the ingested HpD triggers the destruction of the midgut and inhibits the defensive enzymes, viz acetylcholine esterase (AchE), superoxide dismutase (SOD), catalase (CAT) and glutathione- S-transferase (GST). In the current study, HpD was investigated as photoinsecticide against 3^rd larval instar and adults of a myiatic fly, Parasarcophaga argyrostoma (Robineau- Desvoidy) (Sarcophagidae: Diptera). Third instar larvae and adults were fed baits containing 5×10^-2, 5× 10³, 5× 10^-4, 5× 10^-5, and 5× 10^-6 ppm of HpD. Mortality ratios were recorded at different post treatment sunlight exposure periods. The biochemical study of the impact of one median concentration, 5× 10^-4 ppm, proved its ability to cause damage that may be beyond repair for some defensive enzymes. In addition, fatal histopathological changes were detected in the midgut epithelium. The study showed that, HpD could be an excellent pesticide against the larvae and adults of the myiatic flies.