Forensic entomology is the study of insects and other arthropods and their connection to legal issues. Forensic entomology includes arthropod involvement in murder, suicide, rape, and physical abuse. 

     Arthropods eat dead vertebrate bodies, and recycle organic matter in our ecosystem. After a death, one of the first groups of insects that arrive on a dead vertebrate are usually blowflies. The female oviposits two days after the death of the vertebrate, and the blowflies then go through growing stages. We can calculate the amount of time since the egg was laid if we know how long it takes the insect to go through the different stages of life. This calculation of the age of the insect is an approximation of the time of death, because the death of the victim usually occurs before the eggs are laid. This period of time depends on the temperature, time of death, and whether the body is exposed or immersed in soil or water. Insects usually lay their eggs on a corpse within two days after the person dies. 

     Insects can also be of help in establishing whether the corpse has been moved after death, and movement of suspects, goods, or cars can be traced with the help of insects. Insect parts or whole insects can be found in car parts, such as in tire treads. By identifying the insects found, and figuring out the distribution of each insect, as well as the species, one can describe the areas where the suspect has been. 

     In crime investigations, there is always an interest to find out how the victim died, because this can be used to find a possible murderer.

     Sometimes the insects are the killers. Bees can inject venom through a sting and if the person is allergic to the venom, he/she can die if they are not treated. In some instances, insects have been used as murder weapons, as in a case when the parents wanted to get rid of their child so they put it in a room filled with wasps.

     Poison can be traced in blood, urine, stomach contents, hair and other fibers. Another source is in maggots that live and feed on a corpse. After a while it will be impossible to sample stomach contents, urine and blood from a dead body, but it will still be possible to take samples from maggots. Some of the chemicals that have been traced in maggots are malathion, mercury, amitriptyline, nortriptyline, cocaine, phenycyclidine, and heroin. These chemicals can tell us when the person died because they can affect the maggots life cycle. High dosages of cocain increase the growth of many sarcophagids. Malathion, which is an insecticide, is taken orally to attempt suicide. If malathion is found in the mouth, throat, or stomach, this will delay in the migration of arthropids. Amitriptyline, an antidepressant, will increase insect growth time up to 77 hours in a certain species of Sarcophagidae. Information about the victims drug use is important in finding the cause and time of death.

     The locations of blowfly infestation on the dead body can be very important in ascertaining the cause of death, for example: if there has been an injury on the body, there will be more of an oviposition of blowflies in that area, than the other uninjured parts of the body. The most common areas of oviposition on dead humans are natural openings. Blowflies like to lay their eggs in the facial region, but if there is a rape that leads to bleeding in the genitoanal area, blowflies will oviposit in these regions. Consequently, if there is a lot of blowfly activity in the genitoanal region, a sexual crime might have occurred. This data would have to be established with other evidence, but could be presented as well.

     In conclusion, the science of forensic entomology is a very significant one. By studying arthropods, one can learn about the nature of the crime; whether it was a murder, suicide, rape, or physical abuse. By studying their movement, one can also learn about what happens after a normal death, establish a time of death, and if the death is suspicious, a cause for it.