Introduction
Forensic entomology is used to determine such crimes as murder, suicide, and other criminal acts by examining various insects instead of using human tissues. This forensic tool is used to determine the postmortem interval of a corpse and the cause of death of a corpse when all other forms of human evidence (human blood, tissues, hair, etc.) are not present at the scene. Forensic entomologists prefer using insects to determine these factors of death because the insects produce similar results as human test materials such as human blood or tissues which yield the best analytical results for the forensic entomologist. The use of forensic entomological evidence has been accepted and used in many courts around the world
The succession rate includes information about the time elapsed between death and the presence of a particular arthropod or insect species and stage (Byrd and Castner, 2010). A dead body will go through very recognizable decomposition stages (physical, biological, and chemical changes) that attract various types of arthropods in each decomposition stage that are needed to determine the succession rate (Monthei, 2009). The most common succession rate estimated by an investigator is the age of larvae and the time interval between death and the arrival of larvae on the corpse (Byrd and Castner, 2010). The knowledge of what insects are supposed to be present and absent based on the season also helps to determine PMI.
Calculation of PMI involves five different arthropod life stages (eggs, larvae, pupae, adult, and carcass) for flies when collecting insects from corpses. The egg stage of the fly is characterized by the laying of between 150-200 eggs, with the exception of some flies lying between 2000-3000 eggs, found on the body in cluster form within areas that provide protection, moisture, and food (Gennard, 2007). Fly eggs are typically shiny and white; the eggs have a similar appearance to that of a grain of rice. The reason for specific placement of eggs on a decomposing body is the fact that the body contains a high quality of nutrients which are used as a feeding source for the fly eggs to