Initial Observations of Fly Color Preference at a Decomposition Scene in Nebraska

Flies are typically the first insect visitors to a death scene. They can be useful in determining post-mortem interval (PMI) estimates and indicating geographical and environmental factors. Flies can defecate, regurgitate, or mark surfaces they land upon, which can mimic bloodshed and bloodstain patterns on objects such as clothing, furniture, or walls. This study seeks to analyze if forensically important flies are more attracted to certain colors, which could influence which objects they may settle on in and around a crime scene. Although death scene environment color preference studies have been conducted with forensically important flies in laboratory conditions, there have been few such studies conducted at outdoor decomposition settings. In this study, one 68 kg pig carcass was placed outdoors at the UNL Crime Scene House, 2320 N. 43RD, Lincoln, Nebraska. The pig carcass was then surrounded by 6 assorted colors of fly paper affixed to wood panels placed at 0.914, 1.83, and 3.66 meters in the four cardinal directions. Fly color preference was then observed and recorded once the pig had reached late decomposition stages, when flies would no longer be active. The findings from this research could have implications for forensic cases where it is uncertain if objects found at a scene contain blood spatter or fly artifacts.