Forensic Entomology 2021 Presentation

Forensic Entomology

Presenter: Crystal JohnstonForensic Entomology Educator

“Forensic” Entomology

Forensic – pertaining to court of law or public debate.

Entomology - Study of insects. Typically, includes related arthropods (spiders, crustaceans).

Forensic Entomology – Use of insects to aid in legal investigations.

Arthropods & Insectshttps://carwad.net/wallpaper-796797

>925 thousand species of insects identified (believe only 20%)

80% of world’s species v. 0.01% human

10 quintillion (18 0’s) individual insects alive v. ~7 billion individual humans

Insect Orders24 Insect Orders

Each order has same key characteristics, mouth parts and type of metamorphosis.

Forensics:Diptera- Fly (150,000 sp)

Coleoptera- Beetle (350,000 sp)[Primates- >400 sp: 15 sapiens]

Insect Development

4 Types of Metamorphosis

Complete: egg, larva, pupa, adult Gradual: egg, nymphs, adultIncomplete: egg, naiads, adultNone: egg, immatures, adult

Insect Development:Complete Metamorphosis

Examples: butterflies, flies, beetles, bees.

Blow Fly Eggs & Larvae

Eggs:• White, elongate

Larvae:● Legless, with soft

bodies and no distinct head covering.

Blow flies lay eggs in clusters on decomposing flesh. The eggs look like small rice grains.

Pupal Coloration and Age

Rodent feces NOT fly pupae!

Pupae darken over time from cream colored to almost black.

Can time of death be determined by puparium?

No, but may provide window for time of death by calculating how long it took the flies to emerge as adults- corpse must have been around at least that long.

Forensic Entomology

Subdivided into three principal areas where legal ramifications are common:

1. Urban2. Stored products3. Medico-legal

Urban Forensic Entomology

Civil law actions involving arthropods that affect man-made structures and other aspects of the human environment.

Examples: school cafeteria, hospital, termites in newly purchased home, bed bugs in rental apartment, fleas from neighbors home, flies from animal agriculture facility, misuse of pesticides

🡪Termites alone are responsible for approx. 10 million $ in litigation per year!

Stored-products Forensic Entomology

Legal proceedings- infestations of arthropods• commercial food products • stored commodities like cereals and kitchen products.

-Entomologists are often hired as consultants by the food manufacturing companies

Examples: insects parts in human food, flies found in canned goods, ketchup, pantry pests

Medico-legal Forensic Entomology

Deals with insects and other arthropods involved in crimes:- murder, suicide, rape, physical abuse, or human and pet neglect

• Most Common - Insects associated with a corpse used to help estimate the post-mortem interval

• Less common - determine if the corpse has been moved or possibly link a suspect with a death scene.

Forensic Entomology Key Players

Black blow fly

Green bottle fly

Blue bottle fly

Screwworm fly

Flesh fly

Dermestid beetle

Sexton beetle

American carrion

Clown beetle

Clerid beetle

Without decomposing insects:● Dead bodies and animals would take

longer to decompose● Air full of foul odors● Environment filled with decomposing

bodies

HISTORY OF FORENSIC ENTOMOLOGY

Flies and Death in the Ancient World

Flies recognized for role in decomposition - amulets with flies ward off evil and prevent destruction of the body.

Fly amulets given to Egyptian soldiers - symbolize persistence and courage

Washing Away of Wrongs (1247 AD)• A training manual for death scene investigators

(53 chapters in 5 volumes) First CSI book!

• Sung Tz’u– Chinese Criminalist (Death Investigator, Lawyer/High Court Judge)

– Discussed insect evidence in death• Rapid appearance of maggots during warmer days• Recognizes that wounds before death will result in unusual

distributions of maggots on the body.

– “Father of Forensic Science”

Early China – Forensic ENT at work

Case of the telltale sickle…In his book, Ts'u recounts the story of a murder near a rice field. The victim had been slashed repeatedly. Investigators suspected the murder weapon was a sickle, a common tool used in the rice harvest. But how could the murderer be identified, when so many workers carried these tools?

The local magistrate brought all the workers together and told them to lay down their sickles. Though all the tools looked clean, one quickly attracted hordes of flies. The flies could sense the residue of blood and tissue invisible to the human eye. When confronted by this jury of flies, the murderer confessed to the crime.

Francisco Redi - 1668

Disproves theory of spontaneous generation of maggots through controlled experiment.

Time 🡪

Italian Physician & Naturalist

Mathieu Orfila - 1848

• Studied insects that colonize corpses

• Records 30 insect species that visit and feed on a human corpse

– Includes blow flies, flesh flies, and the house fly– Notes that beetles arrive after blow flies (insect

succession)

French pathologist

Jean Pierre Mégnin - 1894

Wrote Faune des Tombeaux (The Fauna of the Tombs) and La Faune des Cadavres (The Fauna of Cadavers)

Rigid patterns of insect succession associated with stages of body decomposition

1st group (fresh stage) – blue bottle flies and house fly.2nd group (early decomposition stage) – green bottle flies and flesh flies3rd group (late decomposition stage) – beetles4th group (desiccation) – mites

French Veterinarian

Jean Pierre Mégnin - 1894

• Initiates interest in the idea of insect succession:

– Hough (American) confirms Mégnin’s work with a variety of animals and locations in the U.S.

– Modern research shows insect succession follows patterns• but variability due to time of year, geographic region, state of

body, etc…

“Father of Forensic Entomology” – focused western attention on the utility of insects in forensics

Insect Succession (General US)*

Early Colonizers (Fresh Stage)– Calliphoridae (blow flies)• Lucilia spp., Calliphora spp., Chrysomya spp.

– Sarcophagidae (flesh flies)– Silphidae (Carrion beetles)• Opportunistic species that feed on the corpse are common– Outdoors: ants– Indoors: cockroaches

*Based on recent studies in the United States… But, substantial variation in this pattern among geographic regions.

Stages of Decomposition - FreshNecrophagous insects (feed on dead tissue) begin to arrive:

Blow flies and flesh flies can locate body within hours and begin oviposition.

– Earliest colonizers --

• Summer - Lucilia spp, Chrysomya spp.

• Winter – Calliphora spp.

• Small animals – Sarcophagidae, Silphidae

Blow Flies (Calliphoridae)

● Medico-legal importance○ Primary indicator species

■ Typically, first to find and colonize corpse■ Adults arrive within minutes to hours to feed on liquids

associated with the corpse and to assess corpse for oviposition.

● Often found in very large numbers on the corpse

● Oviposition preference varies by species:○ Carrion, wounds, kitchen waste, animal feces

Blow Fly Oviposition

● Females can lay up to 300 eggs per batch and 2000 per lifetime.

○ Will only oviposit on fresh carrion with moist tissues.

■ Rewetting of carrion by rain can encourage more oviposition.

• Eggs hatch in 12-24 hours-rapid hatching reduces predation

Blow Fly Oviposition

1. Visually assess the body to find natural orifices and wounds.

2. Walk on the body to determine suitable oviposition site – taste receptors on their tarsi (feet).

3. Only place eggs on fresh carrion. Bodies in advanced decomposition are not attractive for oviposition.

4. Corpse must be sufficiently moist for immature development.

Stages of Decomposition – BloatNecrophagous flies very active

– High species diversity

• Mixture of early and late colonizers

• Maggots at various stages typically present

• Predatory beetles begin to arrive – e.g., Staphylinidae, Histeridae (feed on maggots)

• Opportunistic species are very common and abundant– e.g. ants, wasps, cockroaches (competing with predatory beetles for the available maggots. Often plenty of maggots for all.)


Late Colonizers (Bloat to Active Decay)

– Calliphoridae (blow flies)• Phormia regina, Cochliomyia macellaria, Chrysomya rufifaces

– Muscidae (house fly)• Musca domestica, Fannia canicularis



Predators (Active to Advance Decay)

– Histeridae (clown beetle)

– Staphylinidae (rove beetle)


Insect Succession (General US)*Scavengers (Advance Decay to Dry)

– Cleridae (checkered beetle)

– Dermestidae (skin beetle)

– Scarabaeidae (scarab beetle)

– Armadillidae (pill bugs)

Mites may show up very late in the dry stage, but the are rarely recorded in succession charts.


Modern Forensic Entomology

1960’s: real momentum in the U.S. and Europe

– Widely evident that carrion insects had predictable growth rates and behavioral patterns

– Swine carcasses were shown to be suitable for human decomposition studies.

Modern Forensic Entomology

Bill Bass (1980s) (forensic anthropologist)– Anthropology Research Facility (U Tenn)

• aka the “Body Farm” from 1994 book by author Patricia Cornwell

– Classifies 4 stages of human decomposition• Fresh• Bloated• Decay• Dry

Forensic Entomology Today

Forensic Entomology is a relatively new but now familiar science to law enforcement

– Since 1980’s investigators routinely collect insect evidence

1996: American Board of Forensic Entomology

– Board provides professional certifications

Maggot Mass

Can increase heat of decomposition – which speeds up the maggot development rate.

Protection from predation.

Lucilia sericata

Common Green Bottle Fly

Color can range from brilliant blue-green to green to slightly copper colored.

Lucilia cuprina

Bronze bottle flytypically more metallic copper than L. sericata

Insects Associated with Abuse or Neglect

● Physical Abuse – intentional act causing injury or trauma to another person by way of bodily contact.

Lucilia speciesOften earliest colonizers of a corpse

….Will also lay eggs in necrotic wounds (dead tissue).

● Can locate a body within minutes.● Only lay on fresh carrion.● May deposit eggs on dying animals, just before death.

Evidence for Abuse

• Location of wounds can suggest abuse

• After death, presence of maggots in wounds can indicate wounds occurred before death

• Age of maggots in wounds can indicate when abuse occurred.

Physical Abuse• Untreated wounds can lead to myiasis (infestation of

maggots) by blow flies.

– Evidence of infested wounds prior to death may indicate ongoing abuse.

Physical Abuse

Also attracted to necrotic wounds Similar enough to carrion that some carrion flies will colonize the wound (myiasis).

Eat only dead or necrotic tissue.

May not be painful, though it is reported that one can feel them moving in the wound.

Evidence for Neglect

• Presence of maggots in clothing or on body may indicate neglect by caregiver

• Age of maggots indicates period of neglect

Blow fly maggots in wounds – the presence of blow fly maggots in wounds suggests lack of wound care (neglect) even in cases where abuse is not the cause of the wounds.

Insects Associated with Neglect

Neglect – abuse where caregiver fails to provide expected care to another person.

Animals can also be abused or neglected...

Collection of Entomological Evidence

Processing a Crime Scene

1. Forensic science begins at the crime scene not the forensic laboratory!

2. There is no standard crime scene. Every crime is unique in some way.

3. The forensic entomologist is part of the investigative team under the direction of the lead crime scene investigator.

4. Follow approved routes of access to and departure from the body.

Goals of a Forensic Scientist

● Crime scene and evidence must be photographed and documented.

● Create records at the same time as the examination of evidence.

Proper Specimen Collection

Collecting entomological evidence:

1. Recognize as evidence2. Collect properly3. Document properly4. Transport properly

Proper Specimen CollectionProper collection is key to:

1. Identifying insects to correct taxonomic levela. Retain insects in good shapeb. Keep some live immatures to rear to adult

2. Determine age of insects on or near the bodya. Preserve some specimens (boiling water,

alcohol)b. Rear some immatures to adult

Six Stages of Entomological Evidence Collection

1. Visual observations at the death scene2. Collection of meteorological data3. Collection of specimens from the body4. Collection of specimens from surrounding area (up to 30 ft)5. Collection of specimens beneath the body6. Collection of additional specimens during autopsy

following detailed inspection of body and clothing or other artifacts.

Six Stages of Entomological Evidence Collection1. Visual observations at the death scene

In Crime Scene Log:a. Habitat of areab. Description of body (clothed/nude, stage of decomposition,

scavenger activity)c. Detailed notes of visible trauma (pre or post mortem)d. Take photos of the body and surrounding area, if allowede. Take photos of insects on or near the body, if allowed

● Note activity of flying adult insects- aerial net to catch, place in alcohol● Record insect life stages present on/near corpse● Note locations of maggots or other immature insects on or near the body

Six Stages of Entomological Evidence Collection 2. Collection of meteorological data

Critical for accurate estimate of the age of insects collected from the body!

1. Ambient air temperature (1 m above ground)2. Body surface temperature (top of body)3. Maggot mass temperature (if maggot mass is present)

-MM temp can be up to 20 C higher than ambient – can introduce considerable error in development time determination if not accounted for!

4. Soil temperature beneath body

Six Stages of Entomological Evidence Collection 2. Collection of meteorological data

● Document how long the body would be in direct sun or shade each day● Record any evidence of recent rain● Later, collect official weather data from National Weather Service Station nearby

for the period since victim was last seen alive.

● Special cases:➢ Buried bodies – collect temperatures at buried location➢ Within homes – check thermostat for temperature regulation, were windows

open or closed - for correlation to NWS station.➢ During Autopsy – how long was body stored in cooler, at what temp?


DO NOT DISTURB THE BODY OR ANY POSSIBLE EVIDENCE!

1. Record collections on a Specimen Collection Log.a. Be careful to note body location where insects were collected.b. Record disposition of samples (in alcohol, saved for rearing, etc..)

2. Collect crawling arthropods on bodya. Includes ants, beetles, newly emerged flies, incidental insects.b. Collect with light forceps and place into alcohol.c. Do not place live with other insects as many will be predatory.

3. Collection of specimens from the body

Six Stages of Entomological Evidence Collection 3. Collection of specimens from the body

B. Collect 20-30 eggs or maggots from each body location and place into separate labeled vials for preservation

a. Be sure to collect from the head or body openings as these are likely to be the oldest immature flies.

b. Collect a range of maggot sizes at each location.-May be different species or different ages

c. Kill using near boiling water to fix proteins. Transfer dead eggs and larvae into alcohol for storage.

d. This will fix these life stages for later analysis.

Six Stages of Entomological Evidence Collection 3. Collection of specimens from the body

These will be used to calculate maggot age at the time of collection.

Maggots:

a. Foil pouch -cube of beef liver -vermiculite (place to pupate).b. Separate hairy and smooth maggots (hairy maggots are predatory).c. Separate other maggots that look different.d. Place maggot rearing pouches in cooler with ice for transport.


4. Collection of specimens from surrounding area (up to 30 ft)

Look for migrating larvae or pupae in the area around the body (collect as above)

1. Look under nearby objects, including leaf litter if outdoors2. Maggots may burrow into the top 1-2 inches of soil outdoors

Special case: Buried bodies or bodies in enclosures (homes)

a. Collect adult insects accumulating at locations where decomposition odors are escaping

Six Stages of Entomological Evidence Collection 5. Collection of specimens beneath the body

GET APPROVAL OF LEAD INVESTIGATOR!

❖ Many arthropods will be found beneath the body where they are more protected from predators and from desiccation.

❖ Collect arthropods as in earlier sections❖ Collect leaf litter and soil beneath body and place into large bags for later

analysis● Sift through litter or use Berlese funnel to drive out insects


6. Collection of additional specimens during autopsy following detailed inspection of body and clothing or other artifacts.

❖ Not as useful as insects collected at the scene due to variation in temperatures during transport and storage of body.

❖ But provides more thorough examination opportunity

❖ Clothing in particular should be inspected for fly/beetle pupae● Look closely at cuffs, pockets, seams● Inspect the body bag for insects that left the body since removal from

the crime scene.

Evidence Labeling1. Proper labeling is vital for accurate analyses of collected

specimens.2. Labels for insect specimens should contain:

i. Case # (if known)ii. Date/time collected

iii. Location on body that insect was collected fromiv. Sample ID# (from specimen collection log)

3. Labels are written in pencil (ink dissolves in alcohol)4. For specimen containers: labels are placed inside containers with a

duplicate outer label for ease of reading.

Procedures in the Entomology LaboratoryA. Processing live specimens

1. Ensure chain of custody – sign out specimens from lead investigator.

2. Keep live specimens in maggot rearing pouches under refrigeration (with blue ice) during transport to reduce development during this time period-insects will live but not grow or age!

3. Upon arrival at laboratory, place live insects into temperature cabinets with constant temperature and relative humidity.

Forensic Entomology 2021 Presentation

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