The application of insects
and other arthropods
to legal issues. This includes the study of industrial
forensic entomology deals with information insects can provide in severe criminal cases such as murder, suicide and rape, but also includes physical abuse and contraband trafficking.
Estimating time of death using insects
Many insects are carrion feeders, eating dead vertebrate bodies. One of the first groups of insects that arrive on a dead vertebrate is usually blowflies (Diptera: Calliphoridae). Usually the female oviposits (lays eggs) within two days after death of the vertebrate. Then the blowfly goes trough the following stages:
Because it is known how long it takes to reach the different stages in an insects life, one can calculate the time since the egg was laid. This calculation of the age of the insects can be considered as an estimate of the time of death. But even if the estimate of the insect age is correct, the death of the victim (usually) occurred before the eggs were laid. This period is quite variable and depends on temperature
, time of day the death occurred, time in year the death occurred, whether the corpse is exposed or immersed in soil or water. As a general rule insects will lay eggs on a corpse within two days after the corpse is available for insects.
Cause of death
There are often instances where the insect itself is the cause of death. Wasp and bee stings can kill, especially those who are sensitized. There are unfortunate cases where insects have been used as a murder weapons, such as locking a child in a room full of wasps ...
Maggots can be used to look for poisons in the corpse which they infect. At times after death when it is impossible to sample the stomach contents or blood composition, skins from pupae and dead larvae can be analyzed for the chemicals contained. Certain poisons affect larval growth, and these can be assayed for as well.
Using insects to track movement
When insect bodies, or parts of bodies get stuck to corpses, or tire treads or other materials, they can help investigators correlate the source of the item with the expected distribution of that insect. This has often been used to find the source of contraband, such as marijuana, by the insects found with them.