E NTOMOLOGY

A part from bacteria and fungi, insects are the most important processors of dead animal and human remains Insects utilize decomposing tissues as a food source and a place to rear their young They have a highly developed sense of smell and means of locomotion Flies are attracted to the odors produced by gases and body fluids oozing from the natural body openings and to blood escaping from wounds

Eventually the skin, underlying organs, flesh and bone become attractive to other groups of scavenging insects Burial delays decomposition by excluding air borne bacteria and the normal succession of insects; --insects that do get to the corpse vary with depth of burial, type of soil, presence of moisture and other factors Forensic entomology is based on the analysis of insects and other invertebrates which sequentially colonize a corpse as decomposition progresses and on the rates at which various stages of their offspring develop

Entomology is useful in determining manner of death, movement of cadaver and length of the postmortem interval (time of death) Most important insects are flies (Diptera) and beetles (Coleoptera) Flies, whose larvae are capable of living in a semi-liquid medium, are the 1st to colonize remains Maggots are responsible for the dramatic consumption of organs and tissues Later when dried, species of other insect groups (beetles) arrive

Blowflies 1st to arrive, only minutes to a few hours after death Will lay eggs immediately or feed on protein-rich fluids from corpse 1st Bodies with no trauma: flies feed and lay eggs in the natural body openings 1st because adult blowflies have soft, tongue-like mouth parts which are not capable of piercing skin; openings also provide moist, humid cavities which enhance egg hatching and larval survival

Blowflies Bodies with trauma: feeding and eggs also seen on open wounds Eggs have appearance of grated cheese Colder months: eggs harder to find and are fewer Eggs typically hatch within 1 to 3 days, depending on species and environmental conditions When hatch, produce small, relatively featureless, worm-like creatures called larvae or maggots

Blowflies Larvae grow rapidly, passing through 3 moults (instars) before becoming fully grown Larvae are responsible for disseminating bacteria and secreting enzymes, which enable them to consume virtually all the soft tissue Can be used in qualitative identification of drugs Larvae become fully grown within several days or weeks After reaching 3rd instar, larvae crawl away from the corpse, burrow down into the soil, and secrete a hardened casing around their body; this process is called pupation

Blowflies Eventually emerges as an adult blowfly Blowfly species differ in their abundance from region to region, habitat to habitat, and season to season Ex. Northern US B lue blowfly most common in cooler months Bronze blowfly most common in warmest parts of the summer Green blowfly seen on corpses in the open Black blowfly see on corpses in the shade

After blowflies other insects, especially beetles colonize the corpse to feed and reproduce (they like the drier remaining tissues) Other types of flies also colonize the remains Representative samples of all adult and immature insects collected from corpse, inside and beneath

Entomology Lab Purpose: to estimate time of death using entomological data New Terms: entomology, ecological succession, secondary succession, maggot Data: make a data table for each case that includes species and length of maggot or pupa Analysis: label each case and then answer all questions for that case (should be a total of 15 questions)