User:Jennahughson/Forensic entomology

Medico-legal forensic entomology[edit]
In cases of abandonment or neglect, the presence of myiasis may be noted. The latter can be described as blow flies colonizing a human or animal in life; or in general, the infestation of living vertebrate animals with dipteran larvae. Essentially, this insect succession will feed on the organisms living tissue, ingested food or liquid body substances. However, it is imperative to be cautious of the confusion myiasis may cause in a forensic context. This said, if the victim or found remains were colonized when alive, and prior to being discovered, the entomological evidence would be indicting time of neglect or injury, rather than time of death.

Reference:

Haglund, W. D., & Sorg, M. H. (2002). Chapter 9: Insects Associated with the Body: Their Use and Analyses. In Advances in forensic taphonomy: Method, theory and archaeological perspectives (pp. 181–182). essay, CRC Press.

Moisture levels [edit]
Rain and humidity levels in the area where the body is found can affect the time for insect development. In most species, large amounts of rain will indirectly cause slower development due to drop in temperature. Light rain or a very humid environment, by acting as an insulator, will permit a greater core temperature within the maggot mass, resulting in faster development. "In general, when taking data from a crime scene, it is important to consider that maggot masses can increase the body temperature significantly; essentially speeding up their development and decomposition process. However, the temperature only increases when maggots are in their third instar stage of development."

Flies
Flies (order Diptera) are often first on the scene. They prefer a moist corpse for their offspring, maggots to feed on. The most significant types of fly include:


 * Blow flies – Family Calliphoridae- Flies in this family are often metallic in appearance and between 10 and 14 mm in length. In addition to the name blow-fly, some members of this family are known as blue bottle fly, cluster flies, greenbottles, or black blowfly. A characteristic of the blow-fly is its 3-segmented antennae. Hatching from an egg to the first larval stage takes from eight hours to one day. Larvae have three stages of development (called instars); each stage is separated by a molting event. Adding: "During each molt, the insect will shed off a part of their body. Between two successive molts, they shed their outer layer, as well as their internal craniopharyngeal skeleton or mouthparts (Insect mouthparts). The latter is useful in purposes of identifying larvae species and Pupa. Moreover, the lining of their tracheal system is shed as a result of molting too."

Blow flies – Family Calliphoridae- Flies in this family are often metallic in appearance and between 10 and 14 mm in length (added citation)

Larvae have three stages of development (called instars); each stage is separated by a molting event. Molting can be defined as the process of new cubicle production while subsequently shedding the old cuticle.

"The typical habitat for blow-flies are temperate to tropical areas that provide a layer of loose, damp soil and litter where larvae may thrive and pupate." Someone plagiarized this I found it directly word for word from another site... I will change the wording and add a citation.

Larvae's ideal habitat regarding pupation are locations possessing loose, damp soil and litter. The latter can consist of temperate and rather tropical areas.

original text: Moths (order Lepidoptera) specifically clothes-moths – Family Tineidae – are closely related to butterflies. Most species of moth are nocturnal, but there are crepuscular and diurnal species. Moths feed on mammalian hair during their larval stages and may forage on any hair that remains on a body. They are amongst the final animals contributing to the decomposition of a corpse.

edit: Moths (order Lepidoptera) specifically clothes-moths – Family Tineidae – are closely related to butterflies. Most species of moth are nocturnal, but there are crepuscular and diurnal species. During their larval stages, clothes moths tend to feed on mammalian hair. They are amongst the final animals contributing to the decomposition of a corpse. This said, adult moths lay their legs on a carats subsequently to fly larvae having had heir presence on it.

original:


 * Rove beetles – family Staphylinidae – are elongate beetles with small elytra (wing covers) and large jaws. Like other beetles inhabiting carrion, they have fast larval development with only three larval stages.

edit:

Weather:
 * Rove beetles – family Staphylinidae – are elongate beetles with small elytra (wing covers) and large jaws. Rove beetles have a four stage life cycle; egg, larvae, pupa and adult.

Insects are poikilothermic animals; thus meaning their level of activity is substantially depended upon their surrounding environmental conditions. An increase in the temperature will result in an accelerate of the insects metabolism; hence resulting in an increased activity. Mock Crime Scene: added

Pigs are the most frequently utilised model in an attempt to gather data regarding forensic experimental analysis. The latter is highly proportionate to human nature due to our overlapping characteristics with the mentioned species. These interrelated components include: subcutaneous fat stores, skin thickness, range of adult body mass, hair covering, and omnivorous diets.

before edit:

Some of the morphological differences that can help identify the different species are the presence/absence of anastomosis, the presence/absence of holes, and the shape and length of the median area.

after edit:

Some of the morphological differences that can help identify the different species are the presence/absence of anastomosis, the presence/absence of anterior and posterior spiracles, the cephalopharyngeal skeleton as well as the shape and length of the median area. before edit:

Medico-legal forensic entomology[edit]
Medicolegal forensic entomology covers evidence gathered through arthropod studies at the scenes of murder, suicide, rape, physical abuse and contraband trafficking. In murder investigations it deals with which insects eggs appear, their location on the body and in what order they appear. This can be helpful in determining a post mortem interval (PMI) and location of a death in question. Since many insects exhibit a degree of endemism(occurring only in certain places), or have a well-defined phenology (active only at a certain season, or time of day), their presence in association with other evidence can demonstrate potential links to times and locations where other events may have occurred. Another area covered by medicolegal forensic entomology is the relatively new field of entomotoxicology. This particular branch involves the utilization of entomological specimens found at a scene in order to test for different drugs that may have possibly played a role in the death of the victim. The analytical perspective behind these methods essentially relies upon the fact that the presence of drugs within the carcass has an effect on the growth and morphology of the insects subsequently ingesting the toxins from the corpse. However, due to these morphological alterations resulting on the insects in question, this can potentially lead to an erroneous postmortem interval interpretation when basing an estimation on the specimens physical developement.

want to add: how they test for drugs (maggots ingested), how insects can depict injury / wound location as they tend to be attracted to openings (whether it be natural body orifices or wounds). Medico-Legal (injury determination through entomology): Blow Flies

Entomology can also be of aid in medico-legal cases when depicting the site of an injury; this is due to their preference of alimentation. When eggs laid on the corpse by blow flies subsequently hatch into first instar (ie, first stage larvae), they require a liquid protein meal. However, due to their minute size and fragility, they are unable to break skin themselves to attain this nutrition. Therefore, the female ensures to lay the eggs near a wound site or natural orifice to provide blood, mucosal layer and body fluids that are accessible for an easier feed. wasps:

Wasps, ants, and bees (order Hymenoptera) are not necessarily necrophagous. While some feed on the body, some are also predatory, and eat the insects feeding on the body. Thus meaning they are parasitoids (Parasitoid wasp). These Hymenoptera lay their eggs within the eggs or pupae of other insects; essentially causing the death of host insects. Bees and wasps have been seen feeding on the body during the early stages.[citation needed]. This may cause problems for murder cases in which larval flies are used to estimate the post mortem interval since eggs and larvae on the body may have been consumed prior to the arrival on scene of investigators. Wasps

Wasps also being to the family Pteromalidae. The latter can lay single or multiple eggs. They oviposit in pupae of muscoid flies (blow flies). Subsequently to wasp eggs hatching, larvae will feed on the fly developing within the puparium; leading to its death.