Forensic Entomology

Veterans Tribute CTA Forensics Program

Say What?Forensic (think legal) + Entomology (study of bugs).Forensic entomology is the name given to any aspect of the study of insects and their arthropod counterparts that interact with legal matters.

Forensic entomology is also known as medicolegal or medicocriminal entomology

Forensic Entomology Roles

Because it is primarily focused on violent crimes, medicolegal entomology primarily focuses on:• The determination of postmortem interval (PMI) cases

involving sudden death, and specific investigative purposes (local, weather, determination of injures, etc.)

• Inferences made after the examination and identification of arthropods collected from or near a corpse.

The History The first recorded account in history of someone using forensic entomology for judicial means:

1235 A.D. The Washing Away of Wrongs, written by Sung Tz’u as a guidebook for coroners.

The History The text describes a murder by slashing which occurred in a Chinese village. The local death investigator was dispatched but questioning gained no information.

He then ordered all the villagers to bring out there sickles and lay them down before a crowd.

Flies became attracted to one of the sickles and the owner subsequently confessed to the crime.

Forensic Entomology Use

Human Corpses, whether they have been produced naturally or the result of foul play, are processed by insect decomposers in the same manner as any other piece of carrion.

Forensic entomology therefore, is based on the analysis of the insects and other invertebrates which colonize a corpse as decomposition progresses. Entomological information can be extremely useful in determining manner of death movement of the corpse and length of PMI.

Carrion

Importance of Blow FliesFly species differ in abundance from region to region, from habitat to habitat, and from season to season.

In the northern US for example, a blue bottle, Calliphora vicina, fly is more abundant during the cooler parts of the year, whereas the green bottle fly, Phaenicia sericata, dominates corpses during warmer times.

Calliphora vicina

Phaenicia sericata

Importance of Blow FliesFly species differ in abundance from region to region, from habitat to habitat, and from season to season.

Another green bottle, Lucilia illustris, fly frequents corpses located in open, brightly lit habitats, whereas the black blow fly, Phormia regina, prefers shade

Lucilia illustris

Phormia regina

Importance of Blow Fly EggsBlow fly eggs can provide investigators with an accurate estimation of PMI, narrowing investigative efforts.

Blow fly eggs are small (2 to 3 mm), whitish yellow, and elongate. During warmer seasons they are frequently packed into natural body opening s and wound sites in large numbers and visible to the naked eye.

Importance of Blow Fly EggsBlow fly eggs will typically hatch within one to three days, dependent on species and environmental conditions.In temperate areas during colder months, their numbers may be fewer and the eggs will often be in more discrete locations.

Importance of Blow Fly MaggotsMaggots grow rapidly, passing through three growth steps (instars) punctuated by molts before coming fully grown.Typically large numbers of larvae hatch together and move around the corpse as a group. In doing so, they disseminate bacteria and secrete enzymes which enable them to consume virtually all the soft tissue.

Importance of Blow Fly PupariaAfter reaching the third instar, fly larvae undergo a dramatic behavioral change during which they crawl away from the corpse, burrow down into the soil, and form a puparium containing the pupa.Blow fly puparia are small, football-shaped objects, about the size of rat fecal droppings, and are reddish to dark brown in color.

Importance of Blow Fly PupariaThe process of pupation involves the “tanning” of the larvae’s outer skin, forming a casing around the body. The adult fly develops within, emerging 7-14 days later.

Empty puparia are extremely durable and can remain in the soil near the corpse for hundreds of years. Pupa may be found in remote sites, beneath bedding, boxes, in drains, or beneath clothing.

Importance of Beetles and OthersBesides blow flies, a wide variety of other types of insects also colonize carrion. These insects are attracted to the corpse in a orderly, progressive process termed succession.

Rove beetles, carrion beetles, clerid beetles, sap beetles, checkered beetles, scarab beetles, and dermestid beetles all feed on the drier remaining tissues as well as on the maggot mass.

American Carrion BeetleNecrophila americana

Read more on mites getting in on it too!

Checkered Beetle

Sap beetle

Insects can be a valuable tool in investigations of homicide, suicide, untimely death, and other violent crimes. Accurate forensic determinations are possible only when representative specimens are properly recognized, collected, preserved and forwarded to a qualified entomologist.