Forensic Entomology Study of insects and their relation to legal issues

Types of Forensic Entomology Medicolegal- Criminal acts/legal issues that involve insect infestation of human remains

Urban- Legal issues that involve insects that damage manmade items

Stored Product- Legal issues that deal with insects infesting stored commodities Ex) Insects in cereal

Necrophilous insects Insects that consume dead flesh Carrion-Decaying carcasses/remains

Roles of the Medicolegal Entomologist Calculate time elapsed since death PMI- Postmortem interval Determine if body was moved after death Establish presence & position of wounds

Place a suspect at the crime scene Detect abuse and neglect in children or elderly Toxicology tests - run on maggots, they bioaccumulate toxins

PMI: Postmortem Interval Medicolegal entomologists are called for cases 72 or more hours old Prior to this, other forensic methods are more accurate PMI is calculated in 2 ways: Use maggot age and development Use insect succession

Maggot Age & Development Used within first few weeks of death Accurate to a day or less, or a range of days Blowflies are attracted to corpse very soon after death to lay eggs Their life cycle is predictable: Adult Eggs  Larva 1 Larva 2 Larva 3Pre-PupaPupaAdult

Succession of insects Used from a few weeks of death to a year or more During body decomposition rapid changes occur Stages of decomposition: Fresh  Bloated  Decay  Post Decay  Skeletal Different insects are attracted based on decomposition stage

Fly Life Cycle Blowfly: First bug to arrive at corpse within the first hour of death Lay their eggs in moist areas of corpse. Ex) Nose, armpit, mouth and open wounds Eggs hatch within 24 hours as maggots Reach a length of 1cm after 3 days Next 6-10 days maggots grow, molt and eventually pupate (cocoon) 12 days later adult flies emerge from cocoon.

Figure 2-15  Typical blowfly life cycle from egg deposition to adult fly emergence. This cycle is representative of any one of the nearly ninety species of blowflies in North America. Courtesy E. P. Catts, Ph.D., deceased, and Neal H. Haskell, Ph.D., forensic entomology consultant www.forensic-entomology.com

Factors that Affect Insects Blow flies don’t deposit eggs at night. Flies are fewer during winter months. Extreme cold can cause maggots to go dormant. - Low temps delay maggot development - High temps accelerate maggot development

Entomological Succession The order in which the bugs show up on and in a corpse Blowflies of which there are several species. House flies Flesh flies Rove Beetles feed on the maggots Carrion Beetles also feed on the different stages of fly offspring Hister Beetles Parasitic Wasps

Blow Fly

House Fly

Flesh Fly

Rove Beetle

Carrion Beetle

Hister Beetle

Parasitic Wasp

Insect Collection Procedure Use a net to collect adult insects first Eggs can be collected with a wet paintbrush Use forceps to pick up larvae and pupae Place eggs, larvae, and adults into separate “kill” jar with 75% ethyl alcohol Do not do this to pupae, not necessary because they don’t grow Duplicate samples should be made for live specimens Use separate jars for each colony found

Use pencil for labels, one in the jar and one outside DO NOT use pen because alcohol dissolves ink Labels: Geographic location Date and hour of collection Case # Location of insects on body Stage of development of insects Collector’s Name

Maggot Mouth Hooks

Additional Info

Entomological Succession As the corpse dries, it becomes less suitable for the blowflies, flesh flies and house flies that like a semi-liquid environment Different fly families, the cheese flies and coffin flies, are abundant as the corpse dries Cheese flies have been found in coffins buried up to 3 m deep and in corpses up to 10 years old Coffin flies: It has been calculated that with 98% survival, one pair of coffin flies in a protected place could produce 55 million flies in 60 days

The Final Devouring of a Corpse Eventually, the corpse becomes too dry for the mouth hooks of maggots to operate effectively. The hide beetles, ham beetles and carcass beetles, with their chewing mouthparts, devour the dry flesh, skin and ligaments. Finally, moth larvae and mites consume the hair, leaving only the bones to slowly disintegrate.