Entomological Factors of Human Death - Essay Example

Predators and parasitoids are not directly attracted to the corpses but are attracted to the primary insect communities and thereby indirectly affect the decomposition process and are referred to as secondary insect fauna. Following five stages of decomposition in relation to succession of insect fauna are usually recognized: 1. Fresh stage: The fresh stage commences with death and continues until the start of decomposition. It includes signs of death e. g. livor mortis (purplish body coloration), rigor mortis (stiffening of body muscles) and algor mortis (lowering of body temperature).

Flies of the families Calliphoridae and Sarcophagidae are attracted to the cadaver in this stage. The oviposition occurs and maggot population starts to develop in this stage. 2. Bloated stage: Bloated stage starts when gas production is evidenced due to the activity of anaerobic bacteria, the abdomen swells to a great extent. The corpse body temperature increases immensely due to the breakdown process and the enhanced activities of fly maggots. A characteristic bloat order can also be noticed in this stage.

Calliphorid, sarcophagid, muscid, piophlid and fanniid flies remain present in this stage. Ants and beetles are also present during this stage. These predates on the eggs and larvae of the various species of flies. This stage ends when the body of the corpse collapses due to lacerations in the body wall made by fly maggots. 3. Active decay stage: During this stage the internal body temperature of the cadaver remains very high compared to the environmental temperature. A strong bloating odor is noticed in this stage.

Calliphorid maggots form the major portion of the insect fauna at this stage but adult of these flies decrease in numbers. Sepsid flies also appear during active decay stage. Members of staphylinidae and histeridae families of beetles become abundant. This stage ends when the internal body temperature becomes almost equal to the environmental temperature. 4. Advanced decay stage: The advanced decay stage begins when the post-feeding larvae of the families Sarcophagidae, Calliphoridae and Muscidae leave the cadaver for pupation on a large scale and the body organs change into creamy substance.

Dermestid beetles are present during this stage. Most of the body material is utilized by insects and the intensity of strong bloating odor is decreased in this stage. 5. Dry stage: This stage starts when remaining body mass of the corpse dries up and continues never to end. Bones cartilage and minor fragments of skin is left behind in this stage. Bloating odor vanishes during the advanced decay stage. Dermestid beetles of the previous stage leave the corpse. However, centipedes, millipedes, isopods, snails and cockroaches remain a characteristic feature of this stage.

Other physical factors such as temperature, humidity, light, shade, rain, wind, habitat, season, vegetation and soil type also affect the arrival and colonization of carrion insects and thus affect the decomposition process indirectly. Following results may be achieved by collecting information at the crime scene based on forensic entomology which may help to solve a homicide case. 1. Post-mortem interval: A skillful examination of stage of decomposition, season of the year, insect species composition, temperature, humidity and immature stages of insects can predict the minimum time since death.

Blowflies visit the corpse within minutes of death or murder,