Forensic Entomology

Forensic entomology is using insect biology to determine specific aspects of a crime. It can be used to determine time of death, whether or not a body has been moved, and also if the victim had been intoxicated with any substances. Insects are also prime examples of Locard's principle when solving a crime. The history of forensic entomology dates back to as early as the thirteenth century, and is still been developed today. There have been many cases involving forensic entomology to help solve the crime as evidence, usually about eighty-five percent of all reported species in decomposition are insects.() It has come to be an enormous aspect in forensic science use as evidence.

The first aspect that insects are useful in solving a crime is determining time of death or postmortem intervals. Insects arrive on the body very soon after death. By determining their life cycles, and age it can help estimate time of death. There are four main types of carrion species that are found on a body: necrophagous, predators and parasites of the necrophagous, omnivourous insects, and hunting spiders. () The first group of necrophagous deals with insects that feed directly on the corpse. They usually depend on decaying remains as a food source, so they are very aggressive in their search for food. This is why they arrive at the dead remains only minutes after death. They include both flies and beetles.

Flies are usually the first to arrive to the deceased body. The most common one is the blowfly, which is metallic green or blue. Their life cycle is what helps to determine how long a body has been decaying. Their life cycle is developed in six stages. The first stage is the adult fly, which locates the body to feed and reproduce. Second, the adult fly lays eggs in mucosa membranes, so the eggs are near a food source. These membranes include the eyes, ears, nose, mouth, any open wounds, and the genitals or anus if they are exposed. They usually are not attracted to postmortem wounds, because they do not produce as much blood as perimortem or antemortem, because the heart is no longer pumping the blood. This occurs approximately twenty minutes are death. Then about ten till thirty hours later the eggs hatch with the first instar larva, which is about one to two inches long. It immediately begins to feed on tissue, and increase in size. They then shed their cuticle eleven to thirty-eight hours later to begin their second instar, which is complete in another eleven to twenty-two hours. After another twenty to ninty-six hours the third instar is molted and the larva begins to move away from the body. They move to a drier place away from predators, and parasites to pupate. This process occurs forty to five hundred and four hours later. At first it is a white or ellow color, and then turns to a reddish brown color. After four to eighteen days it becomes an adult fly, it rarely returns to the same body unless there still is a decent amount of tissue left. It usually begins producing five to eighteen days after it completes its pupate.

The other category of necrophagous is the beetles. They along with the flies are usually the first species to arrive to the body. They usually arrive after the body has dried. To differentiate between beetles and fly maggots, you need to look and see if they have any legs. Fly maggots do not have any legs, whereas beetle maggots have three pairs of legs. They are also either white robust and hairless, or dark brown, slender, and quite hairy.

The next types of carrion species are predators, and parasites of the necrophangous. The predators include bury beetles, rove beetles, and hister beetles. They eat the eggs and maggots other beetles and flies. Parasites are made up of ants, bees, and wasps. Small wasps are especially common on the body as a parasitic to the maggots and pupae of flies. They lay their eggs either inside or outside of the maggots or pupa. The eggs then hatch and feed on the developing fly. Depending on what kind of wasp there are also depends on what flies were there.

The third type includes omnivorous insects also including specific types of ants, wasps, and some beetles. They feed on the other insects as well as the body. Wasps will eat other adult flies, and also feed on the fluids from the body. By eating the adult flies it can disrupt decaying for up to a day.

The last species are hunting spiders. They make webs in and around the body to catch insects. The body provides an ideal habitat for the spiders to catch their prey. Although these are the insects that use the body as a source of food they are not the only insects that gain food from the body. There are also soil-dwellers that obtain food from the fluids from the body that seep into the ground. They are usually mites, springtails, roundworms, and nematodes. The fluids that seep into the soil usually stay there for several years after the death.

By determining what insects are on the body, and what stage of development they are in can help determine postmortem intervals, especially in the cases of flies. There are a few factors that do play into delaying or speeding up the decaying process with insects. A few aspects that will delay insect activity are burying a body which also delays decomposition, covering the corpse especially tightly, being in the water, cold weather, and the height of the body from the ground, for example in a hanging. Only insects that can fly can reach the body, so it delays activity, but insects do feed off of the "Drip Zone" under the body, where the fluids have landed. Some factors that speed up the process are the body being outside as opposed to inside, hot and humid weather, and if the body has been burned, because there are so many open wounds that attract the insects.

Another way entomology is useful in an investigation is to be able