Blow flies (Diptera: Calliphoridae) are among the first insects to oviposit (lay eggs) on carrion. The timing of blow fly oviposition is critical for determining a postmortem interval (PMI) estimation, which is the time that has passed between death and corpse discovery. The objective of this investigation is to gain more information about the timing of blow fly oviposition in relation to sunrise. Past research in our lab has shown that blow fly oviposition occurs an average of 4.75 hours after sunrise. This year’s research expanded on previous studies by placing six piglets of different ages, in a remote, wooded area one hour after sunrise. To see if there was a difference in the timing of oviposition related to the age of the carrion, three of the piglets had been thawed for 15 hours (new pigs), and the other three had been thawed for approximately 55 hours (old pigs). The piglets were checked once an hour until oviposition occurred, and it was recorded whether flies and eggs were present each hour. Egg masses were collected and reared to the third larval instar stage for identification using taxonomic keys. The timing of oviposition, in hours after sunrise, was compared between treatments and there was no significant difference found (P=.441). The research was repeated five times in the fall of 2017. The most common flies found ovipositing were Diptera: Calliphoridae, Phormia regina (Meigen) and Diptera: Calliphoridae, Lucilia coeruleiviridis (Macquart). This research has importance in both the scientific and forensic communities, as a more accurate PMI can strengthen the validity of a forensic investigation
