Forensic entomology is mainly used during the investigation of
murders and is the use of insects found on and around the body to determine an
approximate time of death. Considerable research has been done at "The
Body Farm" in Tennessee surrounding the decomposition of bodies after death in
various conditions. Among this research is the timing of insect arrival at
the body and the development or maturation of the insects over time, in various
temperatures, and in
comparison to the decomposition of the body.
When an individual dies, the arrival of insects begins very
rapidly, and when the individual is a victim of a violent crime where there
is blood, urine, or semen present, insect activity may begin immediately.
Blow flies are most often attributed to the use of entomology for
identifying an approximate time of death because they go through their life
cycle in a fairly predictable pattern, which is dependent upon temperature.
Therefore, when an entomologist attempts to determine an estimated time of
death, they must also take into account the weather patterns. Most
people are familiar with blow flies if they have ever went to a location
where there is a public garbage on a hot summer day. Blow flies like
to lay their eggs on or near a food source, which can be rotting garbage,
vegetation, manure, and in the case of crime scenes, dead bodies. Open
wounds are a preferred site for laying eggs, however, mouths, noses, and
genitals may also be a site.
Below is a picture of a common blow fly
on the left and on the right is an example of blow flies on an animal
carcass.
After the eggs are laid on or in the body, they tend to
hatch quite rapidly and become maggots, which begin to consume the body.
Again, depending upon temperature, maggots can pupate and become adults
within a few days, in fact, the entire cycle from egg to adult can occur in
a week. Armed with the expert knowledge of insect life cycles, the
forensic entomologist will collect a sampling of all stages of development
and can then provide an estimated time of death. Insects at the scene
of a crime can also provide information about whether a body was moved, if
there are poisons present and if the victim has been intoxicated with drugs
or alcohol.
