The blowfly is one of the secret weapons in the fight against crime. It was potentially outted by the popular television series CSI, with the lead investigator Gil Grissom using blowfly larvae to establish the probable time of death on more than one occasion. Being brought into the public eye may have helped forensic etymology find its way into mainstream culture, but climate change may make all of that progress moot.
It is important to understand how entomologists use these flies in their work to understand the potential climate change issue. Blowflies are one of the first insects to find dead bodies. They have an extremely acute sense of smell and may be able to detect the scent of dead flesh in as little as 15 minutes. The flies arrive at the body and lay eggs in open wounds and body orifices. Blow larvae goes through three larval stages, each of which can be plotted on a time chart. The affects of temperature on growth are clearly documented, so a trained entomologist can determine the age of the larvae and use it as guide for determining time of death. This timing method gives a minimum time that the body has been dead. Different blowflies have different time intervals – and herein lies the root of the climate change problem
With temperatures warming, the range of different species of blowflies is expanding. This, in and of itself, isn’t a big enough problem to concern forensic etymologists because they can identify the different species and use the indigenous species to and plot their larvae cycles accurately. The newly arrived species, however, may not be genetically or developmentally similar to the population where it is indigenous. This could fundamentally change the life cycle and throw off forensic timing. Also, when these flies start to interbreed it creates an entirely new genetic species whose life cycle has not been fully determined. Thus, the larvae of the new fly is inadmissible in court because there is no forensic standard to compare the lifecycle to.
Another potential concern comes with the addition of new insects into the biosphere. Sometimes new species move into an area and directly affect the native species. This could potentially speed up or slow down the development process of an insect, like the blowfly. If this interaction isn’t tracked and fully understood, etymological evidence could, potentially, give an incorrect assessment of the time of death. In most cases it probably wouldn’t have a strong bearing on the outcome of a criminal investigation, but what if the time of death is off by a full day and this allows the murderer to have a verifiable alibi for that particular time?
It is exactly that question that forensic entomologists fear when dealing with the potential invasion of non-native species to their area. The consequences of climate change and insect migration require the scientists involved in this fairly new branch to remain vigilant and continue to run base tests on indigenous populations to verify the validity of their findings. If, as some entomologists fear, the blowfly populations do cross breed, there will be a lapse in time when larval evidence will be of no use to the court system. This could result in planting that seed of doubt in a jury’s mind and potentially allow a murderer to go free.
Did you ever consider the huge ramifications of climate change on the way our society works? Can you think of any other examples?