In forensic entomology, insect artifacts may cause issues in crime scene interpretation. While research has been conducted on insect artifacts related to blood spatter evidence, little is known these artifacts in sexual assault cases, mainly in their potental to transfer seminal fluid. Recent studies have shown the potential for sustainable human DNA collection from sperm artifacts left behind by flesh flies. Flesh flies feeding on seminal fluid highlights the importance of understanding behavior and preferences of insects and how it impacts investigations. This study aimed to determine whether a preference existed amongst female flesh flies (Sarcophaga bullata) for seminal fluid over other common attractants. To test for preference, an olfactory test was conducted using a Y-tube apparatus. Flies were presented with two choices, seminal fluid and either a control, bovine blood, or bovine liver. Baseline testing was used to validate the accuracy of the olfactometer, using combinations of neutral, positive and negative stimuli; and data interpretation involved two positive stimuli compared to each other. Preferences were quantified by a Preference Index, with a scale of -1 to 1 used to indicate strength of a preference. A moderate preference for seminal fluid amongst flesh flies was observed; surpassing that for blood but less preferable than liver. This preference illustrates the importance of fly artifacts in sexual assault cases. Future studies include analyzing artifacts left behind and their potential for being mistaken for sexual assault evidence in presumptive forensic testing.
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