Forensic EntomologyWhat 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

•http://prezi.com/sm0itymwges0/forensics-life-cycle-of-a-blowfly/

Stage Approximate Size

Color

1st appears

Duration

Characteristics

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!!!!!

What about in the ocean under water? •http://

www.newscientist.com/blogs/nstv/2012/10/sea-lice-mob-devours-pig-from-the-inside-out.html