Midge larvae (Diptera: Chironomidae) as indicators of postmortem submersion interval of carcasses in a woodland stream: a preliminary report.

Data on colonization of rat carcasses by aquatic insects in riffle and pool areas of a small woodland stream were obtained to elucidate patterns potentially useful for determining the postmortem submersion interval of corpses in flowing water habitats. After 39 days, the carcasses had no visual signs of deterioration in the absence of large scavenging animals. Midge larvae (Diptera: Chironomidae) were the dominant insects colonizing the carcasses. No patterns in numbers of larvae over time were evident, but the diversity of genera increased after 29 days in the riffle. Also, Orthocladius larvae did not begin to colonize the carcasses until after 13 days of submersion in the riffle and after 20 days of submersion in the pool. Although separated only by 20 m, the riffle and pool rats had dissimilar faunal assemblages. This suggests that different indices for determining the postmortem submersion interval of corpses based on midge larvae colonization should be developed for these two habitats. This investigation does not provide replicated data, but does shed light on what may happen to mammalian carcasses placed in a stream at a particular time of the year.