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Explore the fascinating world of forensic entomology, using insect life cycles to estimate the time of death in legal investigations. Learn about key aspects such as insect succession, metamorphosis stages, and variables affecting metamorphosis. Discover how insects like flesh flies, blowflies, and beetles play crucial roles in forensic investigations. Gain insights into applications beyond estimating time of death, including linking suspects to crime scenes and detecting drugs in corpses.
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Hours since death = 98.4°F – internal body temperature 1.5 The Process of Death Algor Mortis: Body cooling rate Livor Mortis: skin discoloration caused by pooling of blood – becomes fixed after 5 hours. Rigor Mortis: rigidity of skeletal muscles A pathologist estimates time of death from these factors.
Life Cycle of Insects Metamorphosis egg larva (maggot) pupa winged adult The life cycle of Musca domestica
Forensic Entomology Entomology is the study of insects. Forensic entomology involves the study and use of insects and other arthropods and/or their life cycles to determine how long a body has been deceased to aid in legal investigations. There are three areas of application: Insect damage to structures Infestation of foodstuffs Insects that inhabit human remains The latter category is the subject of this chapter.
Time of Death When a dead body is present, necrophilious insects, or insects that feed on dead tissue, will usually infest it within 24 hours Insects arrive at a decomposing body in a particular order (succession) and then complete their life cycle based on the surrounding temperature. By collecting and studying the types of insects found on a body and their metamorphic stage, a forensic entomologist can estimate the time of death.
Flesh flies Blowflies Houseflies Insects of Death Diptera First to arrive Then Flies can arrive within minutes. They lay eggs that hatch to maggots. Maggots feed on soft, mushy body parts. More insects arrive to feed on the body and each other.
The first and most commonly found insect is the adult blow fly, along with eggs, larvae, and pupae
Coleoptera In rough order of appearance, from within hours to dry decay: Rove beetle Sexton beetle Dermestid beetle Hide beetle Clown beetle Some beetles feed on the corpse, some on maggots, some on other beetles.
Other insects include Several types of beetles that can either be necrophilious or predatory on other insects Predator insects that prey on necrophiliousinsects Omnivorousinsects such as ants and wasps that may feed on the body itself, other insects, or surrounding vegetation Indigenous insects, and/or spiders, may be present, but their presence is usually coincidental to the location of the body
Variables Affecting Metamorphosis The timeframe for lifecycle development is influenced by environmental conditions such as Climate Weather Geographical location Drugs or toxins present in the body Temperature - The higher the temperature (within limits), the faster the growth.
Habitat Fly species can vary geographically according to climate, season, and habitat. Phormia regina Lucilia illustris For example, the fly pictured on the left prefers shade; the one on the right, sunlit areas.
Other Applications of Forensic Entomology Damage to structures, clothing, foodstuffs Location of wounds on a corpse Linking suspect to scene of crime Source of contraband Type of insects can trace vehicle movement Presence of drugs in corpse
