FRSC 3330

Forensic Entomology

The study of insects and their role in forensic investigations, particularly in determining the timing and location of death.

Blow flies

A type of fly belonging to the family Calliphoridae, often used in forensic entomology.

Keys

Published guides or tools used to identify blow flies to species or genus.

Genus

A taxonomic rank below family and above species, used to classify organisms with similar characteristics.

Species epithets

The specific name given to a species, usually in Latin and written in italics.

Authority

The person or group who first described and named a species.

International Code of Zoological Nomenclature

A set of rules and guidelines for naming and classifying animals.

Fly data label

A label used to record information about a specific fly specimen, including species identification.

Post Mortem Interval

The time that has elapsed since a person's death.

Ecology of corpses

The study of how dead bodies interact with the environment and the organisms that decompose them.

Name the four major life history stages

Egg, larvae, pupae, and adults.

Maggots

The larval stage of flies.

Adaptive peak

The optimal combination of traits that allows a species to thrive in a particular environment.

Feast or famine

A situation where there is either an abundance or a scarcity of food.

Putrefaction

The process of decay and decomposition of organic matter.

Mummification

Dry, late stage of decay

Colonization time

The time at which insects first arrive and start to feed on a dead body.

Larvae

The immature form of an insect, typically with a worm-like appearance.

Pupae

The stage in an insect's life cycle between the larval and adult stages.

Intrinsic factors

Factors that originate from within an organism or system.

List some intrinsic sources of variability in carcass colonization (4)

• Late colonizers

• Distance to other nearest corpse

• Number of colonizers available

• Competition from other colonizers

Extrinsic factors

Factors that originate from outside an organism or system.

List some extrinsic sources of variability in carcass colonization (8)

• Moisture

• Sun vs Shade

• Species that arrive

• Distance to nearest corpse

• Commonness or rarity of other corpses

• Predators

• Parasites

• Disease

List some examples of variability associated with the carcass (7)

• Size of corpse

• Presence of drugs

• Food

• Health of the individual

• Amount and location of fat

• Exposure of interior organs and body cavity

• Access (submerged)

Blow flies

Flies that deposit eggs on decaying organic matter.

Burying beetle

Sextant beetle. Order: Coleoptera, Family: Silphidae

Predatory mites

Mites that feed on other insects. Class: Acarina, Family: Macrochelidae

Carcass

The dead body of an animal.

Chitin

A polysaccharide similar to cellulose, found in the exoskeleton of insects.

Cuticle

The outer protective layer of an insect's body.

Cuticular hydrocarbon

external waxy coating of insects.

Spiracles

Small openings on an insect's body for breathing.

Holometabolous

A type of metamorphosis where an insect undergoes complete transformation.

Instars

The three stages of immature (maggot) development.

Head

The anterior part of an insect's body, containing sensory organs and mouthparts.

Thorax

The middle part of an insect's body, where the legs and wings are attached.

Abdomen

The posterior part of an insect's body, containing the digestive and reproductive organs.

Antenna

The sensory appendages on an insect's head.

Dichotomous keys

Tools used to identify organisms based on a series of choices.

Degree day model

A method used to calculate the amount of heat accumulated over a certain period of time, which is used to predict the development and activity of insects.

Degree days

A unit of measurement used in the degree day model, representing the accumulation of heat over time.

Inflection point

The point on a graph where the growth rate changes direction, indicating the optimal temperature for development.

Linear assumption

The assumption that the relationship between temperature and insect development is linear.

Enzymes

Biological molecules that govern insect activity and that are dependent on temperature.

Heat energy

The energy required for insect development, which is dependent on temperature.

Minimum threshold

The minimum temperature required for insect development to occur.

Where is the minimum threshold found on the graph of a Degree Day Model?

The X-intercept of the line of best fit.

Growth rate

The rate at which an insect grows or develops, often measured in days per unit of temperature.

Developmental period

The time it takes for an insect to complete its life cycle, from egg to adult.

Actual developmental period

The observed or measured time it takes for an organism to complete its growth and development.

DD10

Degree days above a temperature threshold of 10 degrees Celsius.

Incubator

A device used to provide controlled conditions for the growth and development of organisms, such as eggs.

Phormia regina

The most common, forensically relevant species of blowfly.

Oviposit

The process of laying eggs.

Generation time

The time it takes for one generation of flies to complete their life cycle.

Degree days > 0°C

The number of degree days accumulated above 0°C.

Correction factor

A value used to adjust data for site effects.

Amplitude

The maximum value of a sine wave.

Wave length

The distance between two consecutive peaks or troughs of a sine wave.

Upper threshold

The maximum temperature at which development occurs.

Lower threshold

The minimum temperature at which development occurs.

Daily maximum temperature

The highest temperature recorded in a day.

Daily minimum temperature

The lowest temperature recorded in a day.

Phormia regina

A species of fly in the family Calliphoridae commonly used in forensic entomology studies.

ADD (Accumulated Degree Days)

A measure of the amount of heat accumulated over time, used to estimate the development and growth of insects.

Sarcosaprophagous

Referring to organisms that feed on decaying flesh.

Degree Day Calculator

A tool used in forensic entomology to calculate the number of degree days based on daily temperature data.

Mites

A non-insect arthopod. Class: Arachnida, Order: Acari.

What non-insect arthropod is an important part of the soil community beneath remains in later stages of decomposition?

Mites.

List some features of mites, including class and order (4)

• Class: Arachnida, Order: Acari

• Small body, <1mm

• 1 body part with small head attached

• 50,000 species described, >1,000,000 estimated species

Tulgren funnel

A heat lamp over a sample, where small insects and organisms fall through into a collecting jar.

What can mites indicate about a corpse?

Possible origins: Macrochelids are usually found in agricultural areas, therefore flies carrying these will also have agricultural origins.

What are mites predatory on?

Fly eggs and first instars.

List some features of spiders, including order (3)

• Order: Araneae

• 8 legs and two body parts: abdomen and cephalothorax

• Predatory on insects and other arthropods, corpses are a source of insect prey

List some features of Pseudoscorpions, including order (5)

• Order: Pseudoscorpionida

• Small (<5mm), two body parts: abdomen and cephalothorax

• Pedipalps and mouthparts distinctive: “pincher like” chelate

• Common in late stage decay, predatory on other arthropods (bed bugs, roaches)

• Can disperse by phoresy attached to flies

What is phoresy?

Phoresy refers to a symbiotic relationship where one organism, known as the phoront, hitches a ride on another organism, the phoretic, without harming or benefiting it.

List some features of sow bugs/pill bugs, including class and order (4)

• Class: Malacostraca, Order: Isopoda

• Associated with decomposing remains (plant and animal) at all stages

• Possible identifier of location

• 13 species in Ontario

What are sow bugs/pill bugs an indicator of?

Habitat.

List some features of centipedes, including class (4)

• Class: Chilopoda

• predatory on other arthropods (bed bugs, roaches)

• 70 species in Canada and Alaska

• Species commonly found indoors, others largely found outdoors

What are centipedes indicators of?

Habitat.

List some features of millipedes, including class (3)

• Class: Diplopoda

• Live in moist habitats, feed on plants and decomposing animal tissue

• >60 species in Canada and Alaska

What are millipedes indicators of?

Habitat.

List some features of springtails (soil insects), including class and order (3)

• Class: Insecta, Order: Collembola

• Jump using a furcula at the end of the abdomen, live in soil all year

• Feed on decaying matter in damp habitats, seepage underneath decaying corpse is ideal

What are springtails an indicator of?

• Record of a body having been in soil

• Body movement indicator

List some features of silverfish, including class and order (3)

• Class: Insecta, Order: Thysanura

• household insect, pest of stored food products

• Associated with dry remains

What are silverfish an indicator of?

Indoor habitat

List some features of cockroaches, including class and order (3)

• Class: Insecta, Order: Blattaria

• Feed on decaying corpses, commonly at lager stage remains

• Nocturnal household pests

What are cockroaches an indicator of?

Indoor habitat, multi-unit dwelling

List some features of earwigs, including class and order

• Class: Insecta, Order: Dermaptera

• Damp habitats, flying insects, predatory

• Commonly found beneath a corpse for daylight shelter

What are earwigs an indicator of?

Indoor habitat, multi-unit dwelling

List early stage beetles and their activity, including order (7)

• Order: Coleoptera

• Come in all sizes, the most abundant and important order

• Predatory beetles arrive early after death and remain through rotting cycle

• Scarab beetles arrive early after death and remain through rotting cycle

• Ground beetles arrive early after death, prey on other insects

• Histerid beetles (black and shiny) arrive in large numbers and feed on maggots

• Burrying beetles arrive early as larvae and adults, feed on remains and maggots

List beetles that arrive shortly after death using common name and family (5)

• Predatory beetles (Staphilinidae)

• Scarab beetles

• Ground beetles (Carabidae)

• Histerid beetles

• Burying beetles (Silphidae)

List features of carpet/museum beetles, including family (4)

• Family: Dermestidae

• Larvae and adults feed on dried skin, hair, fur

• Common indoor dweller, pest of stored products

• Collection of frass (dung), empty larval casings

What are carpet/museum beetles an indicator of?

Mummified remains.

List features of caddisflies, including order (4)

• Order: Trichoptera

• Immatures live in cases made of sand, twigs, or leaves

• rapid consumer of submerged corpses

• Often found in clothing

What are caddisflies an indicator of?

Aquatic habitats (pools, ponds, lakes, streams)

What is the most useful order of flies?

Diptera

List some features of Diptera (2)

• Two wings, hind wings reduced to halteres

• Primitive flies found on carcasses: crane flies, moth flies, fungus gnats, chironomids

What is the common name for Calliphoridae?

Blowflies.