The putrefying flesh of a dead animal is as unpleasant to scientists as to anyone else. As a result, relatively little research has been done on the decay processes that can rapidly reduce a dead body to bones and a few hanks of hair. The dearth of carrion data bothered Clemson University Entomologist Jerry Payne so much that his scientific curiosity eventually overcame his distaste. In some revealing experiments with decaying animal carcasses, he reports in Ecology, he clearly demonstrated that insects take the major role in the decomposition of carrion. He also suggests that study of the insects themselves will tell just when their host died.
On a wooded South Carolina hillside, Payne set out the bodies of piglets that had been still-born or accidentally crushed by their mothers. One group of cadavers was carefully screened and the other protected against animal scavengers but fully exposed to insect invasion. Then the patient entomologist settled down for a decomposition watch. Within five minutes, the first flesh-eating flies arrived to begin feeding on the unscreened piglets. During the next few weeks, 522 species of tiny morticians —most of them insects—arrived to join the feast. Among them, Payne identified "3 phyla, 9 classes, 31 orders, 151 families and 359 genera." By the eighth day, the only piglet parts that had not been consumed were bones, cartilage and dry skin.
Each successive stage of decomposition, Payne found, was characterized by the arrival and departure of particular groups of insects. With this information, he says, even if a body's decomposition were so advanced that a pathologist could not determine the time of death, the character of its insect population would be a dead giveaway to an experienced entomologist.
As might have been expected, Payne's screened piglets fared much better than the unscreened. After bloating and then dehydrating for two weeks, they became mummified and showed little evidence of change for about two months. After 100 days, they began to disintegrate under the attack of bacteria and fungi.
The experiments demonstrate, Payne reports, that insects and their larvae hasten decomposition not only by feeding on the carcass, but also by spreading bacteria and by the simple mechanical process of burrowing through the flesh. "If it weren't for insects," Entomologist Payne says, "we'd be up to our necks in dead bodies."