Date of Submission


Document Type



R. Christopher O'Brien, Ph.D.


Pupation Rate, Emergence Rate, Blowflies, Time Since Death


Ethinyl Estradiol, Estrogens


Ethinyl estradiol, Estrogen, Phormia regina, Blowflies, Human decomposition


After death, blowflies are attracted to decomposing remains for feeding and reproduction purposes. Since blowflies are usually the first species to colonize a set of remains, they are important to forensic scientists when estimating the time since death. Using the knowledge of the life cycle of a blowfly and any interferences of the environment that can affect the development, forensic entomologists can estimate the time since the arrival of blowflies, otherwise considered time since deposition. This research investigated how a specific estrogen, 17 a-ethynylestradiol, present in pollutants affects the development time of blowflies, and therefore the time since death estimation. Four different concentrations of the estrogen were used, Control (no estrogen), LD25, LD50, and LDl00. The Lethal dose (LD) values were calculated from the known LDl00 (lethal dose to 100% of the population) value of the estrogen for rats. This research consisted of two phases, the first observing the effect of estrogen inserted into a food source such as sugar, and the second phase involved observing the development time after inserting the estrogen into a protein feed to induce oviposition. The estrogen produced a deterrent effect when placed in the sugar source for the fly colony, however there was not an observed deterrent effect when placed in the protein feed. The study conducted found an impact on pupation time with an increase of estrogen in the feed, and a decrease in percent emergence with the increase of estrogen was observed. However, replicates were limited, and further research would need to be conducted to strengthen statistics.