1. Maggots and Time of Death Estimation FORENSIC ENTOMOLOG Y

3. Entomology is the Study of Insects Images from: www.afpmb.org/military_entomology/usar myento/files/ArmyEntomology.ppt

4. What is Forensic Entomology? Forensic Entomology is the use of the insects and other arthropods that feed on decaying remains to aid legal investigations. – Medicolegal (criminal) – Urban (criminal and civil) “legal proceedings involving insects and related animals that affect manmade structures and other aspects of the human environment” – Stored product pests (civil)

5. Medicolegal Forensic Entomology Often focuses on violent crimes – Determination of the time (postmortem interval or PMI) or site of human death based on identification of arthropods collected from or near corpses. – Cases involving possible sudden death – Traffic accidents with no immediately obvious cause – Possible criminal misuse of insects

6. Insects as Evidence Forensic entomologists use their knowledge of insects and their life cycles and behaviors to give them clues about a crime. Most insects used in investigations are in two major orders: 1 – Flies (Diptera) and 2 – Beetles (Coleoptera) Blow Fly Carrion Beetle Images: Top Right - http://www.insectinvestigations.com/aboutfe.htm, Chart - http://www.clt.uwa.edu.au/__data/page/112507/fse07_forensic_entomology.pdf Species succession may also provide clues for investigators. Some species may to feed on a fresh corpse, while another species may prefer to feed on one that has been dead for two weeks. Investigators will also find other insect species that prey on the insects feeding on the corpse.

7. Forensic entomologists apply their knowledge of entomology to provide information for criminal investigations. A forensic entomologist’s job may include: Identification of insects at various stages of their life cycle, such as eggs, larva, and adults. Collection and preservation of insects as evidence. Determining an estimate for the postmortem interval or PMI (the time between death and the discovery of the body) using factors such as insect evidence, weather conditions, location and condition of the body, etc. Testifying in court to explain insect-related evidence found at a crime scene. What do they do? Did you know? Maggots can be used to test a corpse for the presence of poisons or drugs. Some drugs can speed up or slow down the insect’s development.

8. 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. 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”

9. Postmortem interval (PMI) Forensic Entomology is used to determine time since death (the time between death and corpse discovery) This is called postmortem interval or PMI). Other uses include movement of the corpse manner and cause of death association of suspects with the death scene detection of toxins, drugs, or even the DNA of the victim through analysis of insect larvae.

10. Succession of Insects on the Corpse Estimates of postmortem intervals based on insects present on the remains are based on: The time required for a given species to reach a particular stage of development. Comparisons of all insect species present on the remains at the time of examination. Ecological succession occurs as an unexploited habitat (like a corpse) is invaded by a series of different organisms. The first invasion is by insect species which will alter the habitat in some form by their activities. These changes make the habitat attractive to a second wave of organisms which, in turn, alter the habitat for use by yet another organisms.

11. Ecology of Decomposition Necrophages - the first species feeding on corpse tissue. Includes rue flies (Diptera) and beetles (Coleoptera). Omnivores - species such as ants, wasps, and some beetles that feed on both the corpse and associated maggots. Large populations of ominvores may slow the rate of corpse’s decomposition by reducing populations of necrophagous species. Parasites and Predators - beetles, true flies and wasps that parasitize immature flies. Incidentals – pill bugs, spiders, mites, centipedes that use the corpse as an extension of their normal habitat

12. Forensic Entomology is Applied Biology If it weren’t for decomposition of all living things, our world would fill up with dead bodies. When an animal dies, female insects will be attracted to the body. They enter exposed orifices or wounds and lay eggs or larvae. A forensic entomologist: – identifies the immature insects – determines the size and development of the insects – calculates the growth of the insects and passage through stages of the life cycle in laboratory – compares the growth against weather conditions to estimate time of oviposition

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

14. 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

15. Weather data is also an important tool in analyzing insect evidence from a corpse. Investigators will make note of the temperature of the air, ground surface, the interface area between the body and the ground, and the soil under the body as well as the temperature inside any maggot masses. They will also collect weather data related to daily temperature (highs/lows) and precipitation for a period of time before the body was discovered to the time the insect evidence was collected. Other factors that might affect their PMI estimates: 1.Was the body enclosed in an area or wrapped in a material that would have prevented flies from finding the corpse and laying eggs? 2.Were other insect species present that may have affected the development of the collected species? 3.Were there drugs or other poisons in or on the body that might have affected the larvae’s development? Did you know… The “Body Farm” in Knoxville, Tennessee is a university research facility to investigate human decomposition under various conditions in order to understand the factors which affect its rate.

16. Time of Death can be broadly estimated up to about 36 hours Temperature Stiffness Time of death Warm Not stiff Dead less than three hours Warm Not stiff Dead less than three hours Warm Stiff Dead between 3 to 8 hours Warm Stiff Dead between 3 to 8 hours Cold Stiff Dead between 8 to 36 hours Cold Stiff Dead between 8 to 36 hours Cold Not stiff Dead in more than 36 hours Cold Not stiff Dead in more than 36 hours

17. 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

18. Insect species arrive at a corpse in waves like clockwork Calculate the heat/thermal energy (accumulated degree hour) required for each stage of the Green Bottle Fly’s life cycle. Possibly the greatest potential source of error in using arthropod successional patterns lies in the collection of speciments. Must only be done correctly to accurately sample the insects.

19. Examples of Diptera (Flies) Informational Source: http://naturalsciences.org/files/documents/csi_tg_overview.doc Images: Top Left - http://www.scienceinschool.org/repository/images/issue2forensic3_large.jpg, Middle-Left: http://forensicfact.files.wordpress.com/2008/04/blowfly053.jpg, Top Right - http://users.usachoice.net/~swb/forensics/P1.jpg, Bottom - http://www.deathonline.net/decomposition/corpse_fauna/flies/index.htm Flesh Fly (Sarcophagidae) S triped thorax Blow & Greenbottle Flies (Calliphoridae) Metallic thorax and abdomen House Fly (Muscidae) Cheese Skipper (Piophilidae) Early Stage Decomposition Late Stage Decomposition Life Cycle of a Calliphoridae Fly

20. Image: http://www.umext.maine.edu/images/FlyLife.jpg Information: http://www.kathyreichs.com/entomology.htm and http://www.forensicentomologist.org/ Blow Fly Metamorphosis 1st – Adult flies lay eggs on the carcass especially at wound areas or around the openings in the body such as the nose, eyes, ears, anus, etc. 2nd – Eggs hatch into larva (maggots) in 12-24 hours. 3rd– Larvae continue to grow and molt (shed their exoskeletons) as they pass through the various instar stages. 1st Instar - 5 mm long after 1.8 days 2nd Instar - 10 mm long after 2.5 days 3rd Instar – 14-16 mm long after 4-5 days 4th – The larvae (17 mm) develop into pupa after burrowing in surrounding soil. 5th – Adult flies emerge from pupa cases after 6-8 days. Blow flies are attracted to dead bodies and often arrive within minutes of the death of an animal. They have a complete life cycle that consists of egg, larva, pupa, and adult stages. It takes approximately 14-16 days from egg to adult depending on the temperatures and humidity levels at the location of the body. Adult Eggs Pupa 3 rd Instar Larva 2 nd Instar Larva 1 st Instar Larva

21. Examples of Coleoptera (Beetles) Informational Source: http://naturalsciences.org/files/documents/csi_tg_overview.doc Images: http://www.cals.ncsu.edu/course/ent425/library/spotid/coleoptera/coleoptera.html & http://www.forensicflies.com/beetles.htm Carrion Beetles ( Silphidae) Adults & larvae feed on fly larvae Early to Late Stage Decomposition Late Stage Decomposition Rove Beetles (Staphylinidae) Predator of fly eggs Early Stage Decomposition Hide Beetles (Scarabidae) Usually the last to arrive Clown Beetles (Histeridae) Predator of fly eggs Ham & Checkered Beetles (Cleridae) Predator of flies & beetles; also feed on dead tissue Skin Beetles (Dermestidae) Feed on dried skin & tissues

22. Five Stages of Decomposition Fueled by Insect Activity. Fresh Bloat Decay Post-decay Dry (skeletal)

23. Fresh Begins at death Flies begin to arrive Temperature falls to that of the ambient temperature. Autolysis, the degradation of complex protein and carbohydrate molecules, occurs.

24. Bloat Swells due to gases produced by bacteria Temperature rise of the corpse Flies still present

25. Decay Gases subside, decomposition fluids seep from body. Bacteria and maggots break through the skin. Large maggot masses and extreme amounts of fluid. Unpleasant odor Larvae beginning to pupate. Corpse reduced to about 20% of it’s original mass.

26. Post-Decay Carcass reduced to hair, skin, and bones. Fly population reduced and replaced by other arthropods. Hide beetles are dominant in dry environments. Mite and predatory beetle populations increase.

27. Dry (Skeletal) Does not always occur especially if corpse is in a wet region. Maggots will stay longer and hide beetles will not appear. In wet environments the hide beetles are replaced with other insects. The corpse is reduced to at least ten percent of the original mass. In the last stage (Skeletal Stage), only bone and hair remain.

28. Two Different Maggot Generations These are distinguishable by the length and obvious size difference. The photograph was taken at a time consistent with the influx at 132 hours.

30. The End