Entomotoxicology

Entomotoxicology is a field in forensic entomology that deals with the analysis of the toxins found in carrion-feeding insects (or their shed casings or feces). Investigators can use this information to find which poisons were present in the body at the time of death. Before entomotoxicology, the determination of toxins present was nearly impossible because the body was so badly decomposed that intoxicated tissues and bodily fluids were useless. Ceratin toxins, such as cocaine, can speed the process of development up for some insects, which can impair the determination of a correct PMI; another reason why these substances should be analyzed in carrion feeders.
A few examples include the finding of phenobarbital in the larvae found feeding on the corpse of a woman with a history of suicide attempts. Or a 29 year old known to abuse drugs had maggots with cocaine in them found five months after he had last been seen.
Sometimes, entomotoxicology can help find where victims are from. A young woman's bopy was found decomposed in Inkoo, Finland. Larvae was recovered from the body, reared to adulthood, and found to contain low levels of mercury, which means that the woman lived a place with low mercury pollution. This assumption was proven correct when the woman was identified and found to have been a student in Turku, Finland (which I guess has some mercury pollution?).