Significance of Blowflies in Forensic Entomology
The earliest ever recorded uses of insects on criminal-based investigations occurred in China in the 13th century when a particular farmer was discovered dead. The farmer got murdered using a sharp object and the body found in a field. However, it was concluded that the farmer got slashed with a sickle leading to his death. A sickle was a tool used for farming during those ancient days. During the ensued investigations, all suspects were ordered to present their sickles and lay them on the ground, whereby only one of the sickles attracted blowflies. The blowflies were invited to the sickle because of the small blood traces left on the sickle since they couldn’t be visible to the naked eyes. This sickle attraction of blowflies resulted in a confession from the murderer who admitted to committing the crime (Isaac et al., 2011). This particular confession led to the setting of a stage that gave rise to a specific field referred to as forensic entomology.
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Forensic entomology gets defined as the analysis and study of insects based on their general application relating to criminal investigations. Although this forensic entomology can effectively help in determining other essential factors, for example, cause of movement or death of a corpse, it is primarily useful in the determination of time since the end of an individual or post mortem interval (PMI). Once an individual is deceased and his or her body begins the process of decomposition, insects in immense multitudes get attracted to the body because of the gases and fluids produced. Some of these insects include wasps, bees, mites, ants, moths, beetles, or flies. However, a more common and most telling insect to entomologists is blowfly (Calliphoridae). This telling is because blowflies often arrive within a few minutes from the time of death. During death, blowflies infest the body as the very first insects. To effectively determine the overall PMI, every forensic entomologist should have familiarity with every development stage of blowflies and their larvae. With proper use of these stages in other terms known as the life cycle, they assist in investigations by determining the approximate time of deaths. Once a corpse is discovered or spotted by a blowfly, it deposits or lays its eggs (ovipositioning) in the body’s natural opening, including open wounds found on the body, the nasal openings, ears, and mouth. An approximated 250 eggs get deposited by a single blowfly that hatch to stage one maggot or larvae in twenty-four hours (Isaac et al., 2011). The larvae feed on the corpse and molt into stage two larvae. The second stage larvae continue to consume the body for long hours till it molts into ph three larvae. Therefore, after phase three, the larvae find a new place to pupate after leaving the body. During this particular stage, the larvae skin hardens to a shell used for protection as the larvae metamorphoses to a fly (Simon Fraser University.Ca, 2010).
Pupation exists in two stages. In the first stages, the shell appears in a pale color, which later darkens and becomes brownish after a few hours. During the final days, emergence or eclosion of adult flies or fly occurs. It takes about two weeks for the transformation from egg to an adult fly. However, this particular timeline process may differ depending on temperature, weather conditions, geographical locations, and contaminants (toxins or drugs) in the body (Saferstein, 2015). Focusing on this reason, a forensic entomologist should put all-weather and geographical conditions into proper consideration during the determination of PMI of a deceased individual.
The fact that these essential stages occur in proper sequences and at defined intervals, all forensic entomologists should approximate the amounts of time a body got exposed. This procedure focuses on a specific number of hours to a month or longer if at all other species of insects are considered alongside insect colonization (Saferstein, 2015). It is a crucial step to identify the correct species specimen by forensic entomologists. This step allows entomologists to make accurate determinations. The forensic entomologists might calculate the weight and length of larvae; thus, they can measure the results obtained against referenced data to precisely estimate the age of larvae’s.
Similarly, every stage in the cycle has their temperature requirements and degree days, meaning that through the identification of species and measuring the thermal history against temperature on the scene, the PMI gets a better approximation by an entomologist (Isaac et al., 2011). However, if a body gets exposed in exceptionally long hours, it becomes impossible to determine PMI using insects or blowflies. Nevertheless, these insects may be of great use when identifying forgotten supplementary facets associated with crime. An excellent example of a crime facet that was ignored is the perpetrator and murder weapon discussed in the first case of this paper.
In the murder case of Danielle Van Dam, forensic entomology was utilized effectively both by the prosecution and defense to determine the approximate period in which the young girl was, however, murdered (Saferstein, 2015). In this particular case, a 7-year-old Danielle was reported missing in her home in San Diego, California, on 1 Feb 2002. Danielle’s body was found decomposing after a period of four weeks. The body was dumped and covered in trash twenty five miles away from home. The police had captured one suspect who was Danielle’s neighbor. The suspect went by the name David Westerfield.
Furthermore, the police placed David under twenty-four hours of surveillance on 4 Feb. A specialized team comprised of forensic entomologists was brought in by the defense. This exceptional team of entomologists argued out that Danielle’s body was placed in the site between 16th and 18th February long ago after David was under surveillance.
However, an entomologist with vast experience and a forensic anthropologist gave evidence based on arid and hot weather conditions. These conditions mummified Danielle’s body, partially causing a delay in blowflies’ colonization (Saferstein, 2015). The two experts testified further, claiming that the corpse would have as well been dumped at the said site from 2 Feb. This claim, together with other presented pieces of evidence, for example, DNA samples and fingerprints established on clothing and RV that belonged to Waterfield, was enough evidence to convict David. David got convicted for the murder of Danielle, and he got sentenced to a death penalty.
The methods, techniques, and times may have significantly changed since the help obtained from flies to convict the individual who murdered a farmer in China in the 13th century. However, the blowfly will remain as a best friend to forensic entomologists when it is about determining an individual’s time of death even after all these years.
Similar to the core values of integrity at Saint Leo, forensic entomologists are supposed to bear consistency in their overall craft and shoe honesty when handling matters that could determine the fate of an individual. Not only does this integrity apply to entomologists; instead, it is required that every forensic scientist should be consistent and just in their efforts to apply knowledge. These experts should bear high consistency in their morals too for proper flourishing and advancement of sciences, just like the staff at Saint Leo aspire to flourish and advance in academics and life at large. Forensic entomology bears great significance when applied in crime investigations.
References
Isaac, J., Deepu, M., Pradeesh, S., Vargheese, G. (2011, July). Web. The use of insects in forensic investigations: An overview of the scope of forensic entomology. National Center for Biotechnology Information. U.S. National Library of Medicine. 19 Sept 2015. Retrieved from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3296382/
Saferstein, R. (2015). Print. Criminalistics: An Introduction to Forensic Science (11th Ed). Saddle River, NJ. Pearson.
Simon Fraser University. (2010). Web. Investigating Forensics: Forensic Entomology or the Use of Insects in Death Investigations. 22 Sept 2015. Retrieved from: http://www.sfu.museum/forensics/eng/pg_media-media_pg/entomologie-entomology/