FORENSIC ENTOMOLOGY PTHS 2017-2018 RESCIGNO

What is Forensic Entomology? https://www.youtube.com/watch?v=vwj-fvoLJ3M

Entomology Inquiry – ON CLASSROOM DO NOT SHARE THIS DOCUMENT! This is INDEPENDENT WORK! 1. Define entomology 2. Explain “Time Since Colonization” 3. Multiple techniques used to assist in the work of forensic entomolgy 4. Summarize Eclosion and how it is valuable to an investigation 5. Three different insect species that infest and feed on a body Include image and description Important information each species provides to an entomologist

Forensic Entomology The study of insects and their relationship to time of death. commonly called upon to determine the postmortem interval or "time since death" in homicide investigations.

Entomology based on the age of the insect present "Time Since Colonization" number of different techniques species succession larval weight larval length accumulated degree hour technique

Life Cycle Stages of a Blow Fly 1. Egg 2 – 4. Larva 5. Pupa 6. Adult

Life Cycle 1St Stage  Eggs 2Nd Stage  First Stage Larva hatch from eggs Maggots feed on dead tissue. 3rd Stage  Second Stage Larva Molts from first stage larva 4th Stage  Third Stage Larva Molts from second stage larva Masses of third stage maggots produce enough thermal energy to increase ambient temperature up to 10 deg C

Life Cycle 5th Stage  Third stage Larva molts into Pupa 6th Stage  Pupa develops into adult fly Approximately 2 weeks from egg to adult Depends on species and environmental conditions Temperature/Exposure/Humidity

Life Cycle of the Blow Fly Blow Flies are most commonly the first insects to infest a dead body. Lay eggs around natural body orifices Nose Eyes Ears Anus Penis Vagina Open Wounds (Gun shot, Stab, Puncture wounds)

Accumulated Degree Hours Technique used to determine Eclosion period of time it takes an insect to hatch from a fresh egg. Eclosion times have been tabulated to complete this development in various insect species. In a blow fly, this time has been determined to be 21.2 hours at 20 degrees C ADH = Temperature in C x Eclosion of species

Accumulated Degree Hour Based on a mean temperature of 20 degrees C For a blow fly ADH = 20 deg C x 21.2 hours Average ADH = 424 degree hours for a blow fly to emerge from its egg For a specific environmental temperature  ADH is divided by the temperature

Calculating Eclosion using ADH For a specific environmental temperature Average ADH is divided by the temperature At 25 degrees C  424 hours / 25 = 17 hours Eclosion of a blow fly at 25 C = 17 hours

ADH Review Eclosion for a black blow fly has been determined to be 23 hours. An average ADH for this insect is 424 degree – hours. What was the environmental temperature of the crime scene where these insects were collected? Would you expect the temperature to higher or lower than 20 degrees C? WHY?

ADH Review 424 deg – hours _____________ = Eclosion time Enviro Temp Solve for Enviro Temp. 424 deg-hours Enviro Temp = ____________ = 18.4 deg C 23 hours

Question of the Day Because insects are cold blooded organisms, it can be concluded that A. insects will develop faster when found on bodies in cooler areas. B. warmer air temperature will mean the body will decompose at a slower rate. C. heavy rain will cause insects to develop faster D. Bodies exposed to large amounts of sunlight will see increased growth rates in insects.

ADH Extension: How it is used in a criminal investigation. Example 1 A type of insect has a threshold temperature of 58 degrees F On a day with a high temperature of 68 F and a low of 54 F, calculate the ADH available to its eggs received on the first day.

ADH Extension What is known from the problem? High Temp = 68 F Low Temp = 54 F Threshold Temp = 58 F What is the significance of this temp?

Solving the problem to find ADH 1. Find the average daily temperature Avg Temp = (68+54 F) / 2 = 61 F 2. Subtract the Threshold Temp from the Avg Temp 61 F – 58 F = 3 F This means that an average of 3 degrees of heat was available to the insect eggs. 3. Find the ADH ADH = Temperature x Time 3 F x 24 hours ADH = 72 degree hours on the first day

Calculate the total Accumulated Degree Hours for the first two days High Temp = 76 F Low Temp = 52 F Follow the steps!

Solution: Total ADH for 2 days ADH for day 1 = 72 degree hours ADH for day 2 = 144 degree hours Avg Temp 64 F – Threshold of 58 F = 6 F ADH day 2 = 6 F x 24 hours = 144 degree hours Total ADH = 72 deghours + 144 deghours = 216 degree hours How is this data used?

ADH Sample Problem 2 A body linked to a missing persons case has been discovered. Police are now investigating two possible suspects for murder. You have been called in as the Forensic Entomologist to examine the body and assist the medical examiner.

The body was found fully clothed on the first floor of a single family home. You find maggots in the second instar stage on the body. The temperature within the home was a constant 72 degrees F.

The insect’s threshold temperature is 64 degrees F Data you have on this species of fly is as follows Minimum of 320 ADH to reach the second instar Minimum of 480 ADH to reach the third instar How long has the body been in the home?

Solution ADH = Temp x Time Solve for Time  Time = ADH / Temp 72 F – 64 F = 8 F Time = 320 deg-hours / 8 F = 40 hours Time = 480 deg-hours / 8 F = 60 hours Body has been in home 40 to 60 hours How is this information used?

Decomposition of a Body Insects will immediately colonize a body. Bacteria, Fungi, and animals Depends upon where the body is located Environmental conditions Some insects thrive in the sun vs. shady conditions Also dependent upon stage of decomposition Beetles will consume bone and cartilage Leakage of body fluids will lead to the disappearance of some insects and the appearance of others.

The Missing Children Forensic Entomology at Work Part 1 http://www.youtube.com/watch?v=TqKq6nYK9mA Part 2 http://www.youtube.com/watch?v=0S9oks0-rqU

The Body Farm - Decomposition Nat Geo https://www.youtube.com/watch?v=vwj-fvoLJ3M&t=119s Decomposition of a Pig http://www.youtube.com/watch?v=R1CD6gNmhr0

Stages of Decomposition 1. 4. 2. 5. 3.

Stages of Decomposition 1. Fresh Stage – blow flies Ants 2. Bloated Stage – putrefaction begins Rove beetles and Carrion beetles 3. Active Decay Stage Maggots feed around natural orifices of body 4. Advanced Decay Stage Beetles 5. Dry Stage Centipedes, millipedes, cockroaches

Investigation and Collection of Insects from a Body 1.Inspect foliage and test soil to see if body has been moved. 2. Collect specimens from different areas of the body, clothing, surrounding environment (indoor/outdoor) 3. Collect 100 maggots 4. Collect pupae from body, clothing, hair, soil 5. Collect empty pupae cases from body, clothing, and surroundings

Investigation and Collection of Insects from a Body 6. Collect adult flies 7. Collect beetles 8. Collect any other insects at scene 9. Collect leaf litter near remains of body if outdoors (enough to fill a coffee can). 10. Place all insects in vials with food

Labeling and Exclusions Keep insects collected from different parts of the body separate from one another. Insects would not be present if the body is wrapped in plastic, buried deep underground, and in frozen or freezing temperature/conditions

What are the top causes of automobile accidents? What have you learned about this in Driver’s Ed?

Accident and Criminal Investigations Insects theorized to be within the top 20 causes of automobile accidents What evidence would support this statement? Consider an automobile accident. Examination of the fragmented remains of insects that have impacted and lodged onto the front fascia, windshield, and radiator of automobiles. Yields evidence to the probable path of an automobile through particular areas Pinpointing the location and areas of travel are of unique importance in some investigations

General Applications Detection of abuse in children Neglect in the elderly Automobile/Aircraft accident studies Interpretation of blood spatter patterns Determination of time of death Recovery of human blood from digestive tract Toxicological analysis

NATIONAL GEOGRAPHICS THE BODY FARM https://www.youtube.com/watch?v=rDDl71d3CIM