Forensic Entomology What bugs can tell us about the dead…….

What the insects can tell us…. Flies and beetles follow a life cycle that allow scientists to estimate how long a body has been dead Post Mortem Interval (PMI) is the time that has elapsed since the person died and can be estimated by observing the insect evidence on the body.

Fly Life Cycle

PMI is established by ….. Observing what life cycle stages are present Larva passes through 3 stages called instars which are identified and used to determine the PMI Need to know some larva anatomy to be able to identify the correct instar

Fly Larva Anatomy The anterior end of the larva contains mouth hooks which are used to tear at the flesh of the

Fly Larva Anatomy On the posterior end is the structure that the larva breathes through called spiracles

Spiracles The number of slits in the spiracles helps to identify the age of the larva The shape of the spiracles will differ for various species

Fly Life Cycle Information life-cycle-of-a-blowfly/ life-cycle-of-a-blowfly/ StageApproximate SizeColor1 st appearsDurationCharacteristics

Factors that affect Insect Development Temperature Moisture Wind Time of day Season Exposure to elements Variations among individual insects Use of insects to predict time of death is only an estimate! All environmental variations must be recorded at time of collection!!!!!

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