Forensic Entomology

• Applies the study of insects (arthropods)

to legal issues

Evidence provided by insects…

• Time of death - provided by

maggot instars (developmental

stages) as well as type of insect

present

• Location of death - if a body is

moved, it may house

maggots/eggs of an insect from

the primary location

Insect Stages

1. Holometabolous: Insects that go through a distinct

pupal stage (complete metamorphosis)

Ex. Flies, butterflies and beetles

2. Hemimetabolous: Insects that only partially change

throughout their life cycle (younger stages resemble

adults)

Ex. Cockroaches

Those Deadly Buggers!

Sexton Beetle American Carrion Beetle

Blowfly

Those Deadly Buggers!

House Fly Blow Fly Beetle Larvae

BLOWFLIES / BLUEBOTTLES

• usually the first to inhabit a corpse

• feed on fluids seeping from body, begin to infest

any orifices, laying eggs

Larva - 1st instar (Stage 1) • initially feeds on fluid exuded from the body • migrates into body • hatching to first molt takes 1 day

Larva - 2nd instar (Stage 2) • moves around in maggot mass • first molt to second molt takes 1 day

Larva - 3rd instar (Stage 3) • still moves in mass • greatly increases in size • second molt to pre-pupa takes 2 days

Pre-pupa (Stage 4)

• migrates away from the corpse seeking a suitable pupation site, (usually in soil)

• does not feed

• transforms into pupa

• pre-pupa to pupa takes 4 days

Pupa

• resides within puparium (a thick outer shell)

• undergoes transformation from larval body to adult fly

• does not feed

• pupa to emergence takes 10 days

Adult fly

• mates on emergence from pupa

• feeds on protein from body fluids

• lays eggs on corpse

• emergence to egg laying takes 2 days

Thermal imaging:

Scientists at The Natural History Museum, London, UK, are just beginning to explore the thermal dynamics of larval masses using infrared photography. The temperature of individual blowfly larvae can be measured. The still-born piglet appears untouched by insects in a normal photograph, but thermal imaging indicates an active larval mass in the throat and chest regions that causes an increase in temperature where the larvae are feeding.

The corpse of a 41-year-old medical doctor was found in his bed. The body was partially dried out; parts of the hip region were skeletonized due to maggot activity. In the facial region of the corpse, blowfly maggots were found exclusively in one eye socket. This is an unusual occurrence since on that side, a bed light (40 W light bulb) had been burning during the seven week post mortem interval. All other lights in the apartment were switched off, and no direct sunlight could enter the space where the body was found Obviously, the maggots who usually flee light had used up the one eye that was further away from the bedlight as a feeding source. Since the continuing mummification of the corpse led to a substantial restriction of feeding material, the maggots finally switched to the eye that the light was shining on.