Forensic Entomology

Entomology: The study of insects

Forensic Entomology: The study of insects in a legal context.

• An entomologist’s knowledge is used to determine the time of death range

•  It can also determine:

  • If the body was moved

  • Where the wounds are

  • Whether the victim was poisoned or drugged

Time of death estimation

Blowflies

• Flies that rely on dead organisms to survive

  • Male and female flies need protein for genitalia development

  • Female flies lay their eggs on bodies so maggots will have a food source

• Dead bodies will give off chemical cues and odors, allowing flies to immediately locate them.

• Flies can usually find the body within minutes, from up to 1.6km away

• Flies can only access the body if it’s daytime,  if they are physically able to reach the location, if it’s not winter, and if the weather conditions are favorable

Life cycle

• Young larvae aren’t strong enough to break skin, so eggs must be in a place where food is accessible. 

• Wounds are priority if there are no wounds,  eggs will be laid in natural orifices

• As maggots develop, they will grow slits on their bodies. 

  • Oneslit—first instar

  • Two slits—second instar

  • Three slits— third instar, prepupae stage

Successional colonization

• After the blowflies have left, other insects can colonize the body.

• These are just a few of the types of bugs found in crime scenes.

Other factors

Drugsand toxicology

• When maggots feed on tissue, any drugs or substances they eat will be absorbed into their bodies

• Drugs will affect the insect’s development cycle

• In order to see how much the life cycle has been affected by, insects are taken into a laboratory and raised under the same conditions

  • This is a process called Accumulated Degree Hours (ADH)

• Human DNA can be extracted from bugs feeding on the body

Crime scene location

• Killers will usually hide the body in a safe spot, and come back to it later to dispose of it

• If the insects on the body are native to a different geographical region, the body may have been moved

• Time of death, manner of death, and location are very important to solve death cases

Non-death cases

• Alive humans and animals can have dead tissue on them, which is just as appealing to insects. These dead tissue can be caused by:

  • Unhealed wounds

  • Bed sores

  • Gangrenous or dying tissue

  • Poor hygiene

• Infestation of living human tissue by bugs is called myiasis.

No insects?

Can mean many things:

• The killer took special precautions to make sure the body isn’t found, such as storing it in a sealed off area

• The victim was killed at night (when insects aren’t active), and the body was discovered at night too (before the insects wake up)

• The body was found almost immediately after the victim was killed

• The victim was killed while there was heavy rain/snow/wind

• It was winter (insects are inactive throughout this season)