VOCABULARY: FORENSIC ENTOMOLOGY Cold blooded-organism that depends on the environment to maintain its body temperature. All arthropods, including insects, are cold blooded. The development time from egg to adult depends on the temperature of their environment. Contrast with warm blooded mammals and birds that control their body temperature through metabolic processes.

Decedent-individual who has died.

Ecological succession-Process in which communities of plant and animal species in a particular area are replaced over time by a series of different and often more complex communities.

Forensic entomology-the science of using insect evidence to uncover circumstances of interest to the low, often related to a crime. Insects associated with a corpse can be used to determine time, location and/or cause of death.

Instar-developmental stage of a larval insect. As a larvae grows, it must periodically cast its exoskeleton. The stage between molts is called an instar. Flies undergo 3 instar stages as maggots, called the 1st, 2nd and 3rd instar, respectively.

Maggot-larval instar (stage) of a fly or beetle. Fly larvae typically molt or change stages 3 times before pupation.

Metamorphosis-process in which an organism undergoes a rapid distinct change from young to adult form. Notable in the life histories of marine animals, insects and amphibians. Metamorphosis requires destruction and rebuilding of tissues, involving lysosomes, hormones and changes in gene expression.

Postmortem interval (PMI)-the time elapsed between the death of a person and the discovery of the corpse. Blow flies can locate a corpse within 10-20 minutes of death. The time of first egg laying by these flies is consistent with the time of death.

Stages of Decomposition: a) fresh –begins at the moment of death (corpse looks like a sleeping person) and ends when the body becomes visibly bloated. Blow flies (Calliphoridae) and flesh flies (Sarcophagidae) begin laying eggs during this stage. Blow flies lay eggs but flesh flies deposit newly hatched larvae on the corpse.

b) bloat-begins when the abdomen starts to show signs of inflation due to gasses produced by bacteria within the gut. The greatest number of fly eggs are deposited during this stage. House flies (Muscidae) begin to lay eggs on the corpse. The internal temperature of the body rises to as much as 53 oC (127 oF) due to the action of internally feeding maggots and bacteria. The number and variety of predator beetles increases.

b) active decay-marked by the breaking of the skin and escape of gasses. Due to the combined activity of maggot and bacterial feeding. This stage smells bad due to production of decomposition gasses like putrecene and cadaverine.

c) advanced decay-fly larvae are completing their development and begin leaving the corpse to pupate. The temperature of the corpse drops and the remaining tissues are consumed. From this point on, most insect activity is due to beetles. Flies cannot feed on dry tissues.

d) skeletonization-only 10 percent or less of the original corpse remains, primarily composed of hair and bone.

e) saponification-condition in which the fatty tissues in a corpse are converted to a waxy layer similar in composition to soap(adipocere). Due to bacterial action and alkaline (basic) conditions from soil or embalming fluids in the absence of oxygen. Corpse can undergo saponification starting 2 weeks to 1 month after death. Usually occurs when a corpse is found in wet areas (eg. drowning victim) or after embalming. A corpse in this condition is called a “soap mummy.”

f) mummification-condition in which the body is preserved in an unusually dry place such that activity of internal bacteria or insect decomposers is kept to a minimum.

g) dismemberment-condition in which sections of a corpse have been separated. Can occur due to foul play or predators feeding on the corpse.