The photo of the week series is a weekly series featuring photos taken by our academics and students for our Research Photography Competition, which provides a snapshot of some of the incredible research undertaken across the BU community.
This week’s photo of the week, ‘Post-feeding Blood pattern comprised of the artefacts of the blowfly Calliphora vicina enhanced with Bluestar,’ is by the winner of this years Research Photography Competition, Christopher Dwen, a TTO Demonstrator In Forensic Science.
Blowflies have a high affinity for some bodily fluids such as blood, semen and saliva when other food sources are absent. For this reason, they are frequently found at crime scenes if they have access through open doors or windows.
Because some foods are difficult for a fly to breakdown in their pure forms, it first uses the proboscis (mouth parts) to draw it up, which it then mixes with digestive enzymes to break it down. This food is then expelled, again via the proboscis, and returned to at a later time when it is more easily consumed. Often, this type of feeding behaviour will leave ‘spotting’ stains on a surface as the fly dabs a surface with the proboscis following ‘bubbling’, which involves the fly repeatedly expelling and reabsorbing a bubble of regurgitated liquid (in this case, blood) from its proboscis.
The attached image is of a bloodstain pattern created entirely by just five blowflies (Calliphora vicina), and then enhanced with Bluestar® Forensic latent bloodstains reagent. A petri dish of horse blood in the centre of the pattern was the food source, and the resulting pattern shows the density and distribution on deposited fly artefacts in relation to that source.