Chapter 12 Forensic Entomology © 2012 Cengage Learning. All Rights Reserved

Introduction—Objectives Define forensic entomology. Describe the anatomy of an arthropod. Discuss the life cycle of insects. Estimate time of death using insect evidence. Examine the effects of insects on human remains. Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Introduction—Objectives Evaluate the use of entomological evidence to solve crimes. Describe the impact of weather on metamorphosis. Demonstrate proper procedures for collection and preservation of entomological evidence. Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Introduction—Vocabulary Arthropod—a phylum of animals with jointed appendages and an exoskeleton (from the Greek arthros–jointed; podes–feet) chitin—a tough polysaccharide; the major component of an arthropod’s exoskeleton exoskeleton—a rigid external structure made of chitin and protein (protects, provides a point of attachment for muscles; prevents water loss) forensic entomology—the study of insects in legal situations Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Introduction—Vocabulary invertebrate - organism lacking a backbone larva (larvae, pl) - immature, feeding stage of insects that undergo complete metamorphosis; the stage between the egg and pupa maggot - legless larva metamorphosis - the changes an organism undergoes as it develops into an adult pupa (pupae, pl) - nonfeeding and relatively inactive developmental stage of some insects Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Chapter Summary Forensic entomology is the analysis of insect evidence in legal cases. Insects belong to the phylum Arthropoda, a group of organisms with jointed appendages, segmented bodies, and an exoskeleton. The first documented use of insects to solve a homicide case was in China in AD 1235 Since, scientists have added to the knowledge of insect behavior and life cycle. Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Chapter Summary Insect evidence is valuable in estimating the postmortem interval. There are more than 700,000 known species of insects, but only a few have forensic value. Female blowflies are usually the first insects to colonize a dead body. The extent of decomposition—especially if it is unevenly distributed on the body—provides information for estimating the time (and perhaps manner) of death. Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Chapter Summary Entomologists record and analyze climate and weather information related to the insect samples. Temperature, humidity, and other weather and climate elements affect the insects that colonize remains as well as the progression of the insect life cycle. Processing and preserving insect evidence requires special care, techniques, and materials. Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Bugs Don’t Lie July 9, 1997 Champaign County, Ohio Stepfather, Kevin Neal, claims stepchildren are missing from their back yard Bodies discovered on September 6th were in the late stages of decomposition Autopsies revealed Maggot infestation Absence of blowflies and screwworms Presence of cheese skipper fly in its 3rd instar stage How were these insects evaluated? Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Introduction (Obj 12.1, 12.2) Arthropod—an invertebrate Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

History Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Insects & Forensics (Obj 12.2) Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Insects 29 orders, or related groups, of insects 2 orders are important to forensics Flies (Diptera) Beetles (Coleoptera) Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Insects at Work (Obj 12.3, 12.5) Metamorphosis—the maturation process for insects) Eggs Larvae Pupa Adult Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Postmortem Interval (Obj 12.4, 12.6) Postmortem Interval—the time elapsed since a person died When longer than 72 hours after death, entomology becomes important Within 48 hours the female blowfly lays eggs in moist areas of the body Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Collecting & Preserving Evidence (Obj 12.6, 12.7, 12.8) Observe and record all pertinent factors Weather patterns (rainfall, wind, humidity, temperature, and exposure to light) during the PMI Avoid disturbing insects within several feet of the body Measure distance from body to insects Collect samples of all insect stages on, near, and under the body Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Collecting & Preserving Evidence (Obj 12.6, 12.7, 12.8) 1. Estimates on the types and number of insects 2. Key insect colonizations on and near the body 3. Exact positioning of the body using fixed points, if possible: placement of the arms and legs, the position of the head, and parts of the body in the shade and in the sunlight 4. Locations of eggs, larvae, and pupae on the body Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Collecting & Preserving Evidence (Obj 12.6, 12.7, 12.8) 5. List of opportunistic feeders and other insects (such rove beetles, ants, wasps, and insect parasites) 6. Insect movements (within 20 feet of the body) 7. Natural and artificial influences that might affect the speed of decomposition, such as burning, covering, or burying the body Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Collecting & Preserving Evidence Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Factors Affecting Insect Activity Natural environment and natural light Natural environment and artificial light Artificial environment and natural light Artificial environment and artificial light Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Temperature Readings Ambient air Ground Soil 1 foot above the body 4 feet above the body Ground Soil Surface 10 centimeters below 20 centimeters below Center of a large infestation (if present) Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

More on Collecting and Preserving Capturing live flies with nets Pin flies to a board, or Preserve with 80% alcohol and 20% water Adult flies Eggs Largest larvae Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

More on Collecting and Preserving Label vials with case number collection time date geographic location the location of the insects on the victim the initials of the investigator Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Accuracy Insects begin colonizing at a dead body immediately after death Dependent on season and environment Rate of development of the species can be used to estimate time since death Can give an estimate up to a year

Accuracy Entomological evidence is the most accurate and frequently the only method available to determine the elapsed time since death Due to rigor, algor, and livor mortis being useless after 72 hours

Accuracy Insects are also used to Determine whether the body has been moved after death Determine whether it has been disturbed Determine the presence or position of wound sites Determine whether the victim used drugs or was poisoned Determine the length of time of neglect or abuse in living victims

Insect Biology Insects are the most diverse and abundant forms of life on earth. There are over a million described species- more than 2/3 of all known organisms There is more total biomass of insects than of humans. Insects undergo either incomplete or complete metamorphosis (Egg to larva to pupa to insect) Larva have a soft tubular body and look like worms. Fly species larvae are “maggots”

Image: http://www.nlm.nih.gov/visibleproofs

Decomposition Begins at the moment of death, caused by two factors Autolysis The breaking down of tissues by the body's own internal chemicals and enzymes Putrefaction The breakdown of tissues by bacteria These processes release gases that are the chief source of the characteristic odor of dead bodies These gases swell the body

Decomposition Scavengers play an important role in decomposition Insects and other animals are typically the next agent of decomposition, if the body is accessible to them The most important insects that are typically involved in the process include the fleshflies (Sarcophagidae) and blowflies (Calliphoridae) The green-bottle fly seen in the summer is a blowfly Larger scavengers, including coyotes, dogs, wolves, foxes, rats, and mice may eat a body if it is accessible to them Some of these animals also remove and scatter bones.

Factors Involved in Decomposition In a roughly descending degree of importance, those factors include: Temperature The availability of oxygen Prior embalming Cause of death Access by insects Burial, and depth of burial Access by scavengers Trauma, including wounds and crushing blows Humidity, or dryness Rainfall Body size and weight Clothing The surface on which the body rests

Differentiate between PMI and Time of Death These may not always equate. Post mortem interval is restricted to the time that the corpse or body has been exposed to an environment which would allow insect activity to begin. Closed windows Body in box or bag Cold temperatures Deeper burial

Major Groups of Insects Associated with Cadavers Flies Blowflies Flesh Flies House Flies Cheese Skippers Beetles Carrion Beetles Dermestids Scarab Beetles

Blow Fly Metamorphosis Adult Pupa Eggs 3rd Instar Larva 1st Instar Larva 2nd Instar Larva It takes approximately 14-16 days from egg to adult depending on the temperatures and humidity levels at the location of the body. Image: http://www.umext.maine.edu/images/FlyLife.jpg Information: http://www.kathyreichs.com/entomology.htm and http://www.forensicentomologist.org/

Decay Rates Are Variable Studies of decay rates of 150 human corpses at in the Anthropological Facility in Tennessee (The Body Farm) Most important environment factors in corpse decay: Temperature Access by insects Depth of burial Other Factors Chemical-- embalming agent, insecticides, lime, etc. Animals disrupting the corpse

Determining Whether the Body has been Moved Insects present on the deceased body that are not prevalent to the crime scene can indicate that the victim was murdered elsewhere and was dumped at another location

Drugs Insects that feed on the body of individuals that have been poisoned can be examined to determine what type of drug or toxin the person was poisoned with It is important to note that specific drugs either speed up or slow down larval development Can influence entomologist’s final report

Challenges to Forensic Entomology 3 challenges exist Temperature Temperature of crime scene and the temperature that the insects have been exposed to us unknown Season Entomology is valuable only in spring, summer, and fall Exclusion of insects Insects are excluded based on condition of body

Succession Fresh Bloated 1 2 3 Post-Decay Dry Decay 4 5 6

Five Stages of Decomposition Fueled by Insect Activity. A. Fresh Stage B. Bloated Stage C. Decay Stage D. Post-decay Stage E. Dry Stage

Stage 1 of Decay https://canvas.instructure.com/courses/825004/pages/stage-1-of-decay 7:16

Fresh Stage (Days 1-2) Blowflies have detected the cadaver Eggs are being laid, often around the eye, nostrils, mouth, followed by anus or genital openings Eggs

Stage 2: Bloat Stage https://www.youtube.com/watch?v=M4SuDHpqeUE

Bloated Stage (Day 2-6) Cadaver begins to swell and putrefy Flesh flies appear Small maggots are feeding Putrefaction begins. Gasses produced by anaerobic bacteria inflate the abdomen. Pig’s eye

Stage 3: Active Decay https://www.youtube.com/watch?v=r5ynpWVem0Y

Decay Stage (Days 5-11) Adult blowflies no longer attracted. Large masses of maggots feeding externally and internally Predators and parasitoids of maggots arrive Abdominal wall breaks allowing gasses to escape. Carcass deflates.

Stage 4:Dry Decay https://www.youtube.com/watch?v=uM4hMxub_sE

Post-Decay Stage (Days 10-25) Cadaver is drying out. Large maggots are leaving or have left In dry habitats, remains are skin, cartilage, and bones. In wet habitats, wet, viscous material in the soil under the remains.

Dry Stage Skin and bones Insects with the ability to digest keratin (clothes moths and dermestid beetles).

Stages of Decay Video http://vciforensicscience.weebly.com/forensic-entomology.html

Let’s give it a try … Click the image above or click here to visit the website at http://www.pbs.org/wnet/nature/episodes/crime-scene-creatures/interactive-determine-the-time-of-death/4390/

The End