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FORENSIC ENTOMOLOGY
1. Introduction
a. Insects can give a lot of information about a crime when a
murder has occurred
b. Entomology is the study of the life cycle and distribution of
insects
c. Forensic entomologist is a scientist who studies the life
cycles of insects found on a decomposing body
d. Forensic entomologists can pinpoint the time period of death
and how long a body has been left at the crime scene after
death occurred by looking at
i. What types of insects are found on a body
ii. Where they are at there stages of development
1. Eggs
2. Larvae
3. Maggots
4. Adults
e. There are two basic methods of determining how much time
elapsed since death
i. Development of blowfly larva
ii. Predictable successional colonization of body by
insects
2. What Can Insects Tell Us About A Murder?
a. For entomologists a human corpse at a crime scene is a
changing ecosystem of natural decay
i. microhabitat of food, homes and a place to stay for
many insects
ii. insects become prey for other predatory insects later
b. The waves of insect infestation of a body has predictable
patterns; since scientists have studied the life cycle and
behavior of most common insects
c. The forensic entomologist:
i. Call upon to identify the type of insect present on the
body or at the crime scene
ii. Note where these insects are in their life cycle
iii. Information applied to estimate the possible amount of
time that the human remains were undiscovered and
unprotected after death
d. Insects also provide clues about where the body was located
before being discovered (if a body in the countryside has city
insects it says that the body was in the city before being
moved to the country)
3. Types of Common Insects (“carrion” insect species that feed on
dead organisms)
a. Necrophagous Species:
i. Feed directly on the human corpse
ii. Blow flies and flesh flies
iii. Incredible sense of smell and arrive quickly at the dead
body; as quick as 10 minutes after the person died
iv. Female flies land on the body, feed on the body fluids
seeping out and lay eggs in body’s cavities
b. Predators and Parasites
i. Bugs that are attracted to the dead body by presence
of necrophagous insects
ii. Predators are insects that hunt and eat other insects;
Beetles that prey on eggs and maggots of flies that
feed on the body
iii. Parasites
1. rely on insects like to lay eggs in the other
insects’ egg sacs; lay their eggs on top of the
maggots of necrophagous insects
a. Bees
b. Ants
c. wasps
2. attracted to certain kind of fly so you can
determine what fly was the first to arrive on the
scene
3. this information can give clues on the time of
death and how much time has passed since
death
c. Omnivorous Insects
i. These feed on BOTH the human body and the other
insects
ii. Some of them are so good at catching insects that they
actually slow down the overall rate of decomposition
d. Normal Insects
i. Found on or near decomposing human bodies inhabits
the area; uses the corpse as an extension of the home
ii. Hunting spiders weave webs on body parts; soildwelling organisms that feed on body fluids that seep
into the soil underneath the body
4. Larval Development (see handout)
a. Introduction
i. Flies attracted to body after death
ii. First flies are the blow flies
iii. Flies need a protein meal for gametes to develop
iv. Development is temperature dependent
b. Stages
i. Once laid, blowfly eggs hatch into first stage (first
instar) larvae  rely on liquid protein; wounds, orifices
ii. First instar molts to second instar; larger and can
penetrate skin with enzymes and mouthparts
iii. Third instar voracious feeder that groups in large
masses; generates lots of heat
iv. Nonfeeding stage  wanders away from food site;
soil, carpet, hair or clothing
v. Contracts and pupates; changes into adult fly
c. When using blow fly to determine time since death, you must
know
i. The oldest stage of blow fly associated with the body
ii. The species of insect
iii. Temperature data
iv. Developmental data
5. Collection and Preservation of Insect Specimens
a. Equipment
i. Hand net
ii. Forceps and Digging Tool
iii. Thermometer
iv. Vials, jars, Plastic Bags
b. Supporting Data Needed
i. Previous weather for the area
ii. On site weather data (3 – 5) days
iii. Photos and Videos of Crime Scene
iv. Time of collection
v. Medical Examiner Autopsy report
6. Stages of Decomposition
a. Introduction
i. rates of Human Decomposition depend on
circumstances and location of the body
ii. corpses in hot climates decompose faster than in cold
climates
iii. Decomposition is also effected by the dampness of the
region; humidity
b. Fresh stage
i. Begins at the moment of death
ii. Body temperature falls to that of the air and soil
temperature
iii. Insects like blowflies land on body, feed on body fluids,
lay eggs in cavities and wounds
iv. Eggs take 12 – 18 hours to hatch
v. When the eggs hatch, maggots feed on the body
vi. Flesh flies fly over the corpse and lay more eggs on
the body
vii. Then predators and parasites arrive
c. Bloated Stage
i. Bacteria in the body release gases during putrefaction
ii. Gases bloat the abdomen, then the whole body like a
balloon
iii. Body becomes very hot 127 degrees
iv. Blowflies and flesh flies are joined by houseflies which
all lay countless eggs that hatch at the same time
v. Masses of maggots feeding on the body muscle and
fat
vi. Maggots get bigger and bigger and more predatory
insects are attracted to the scene  more
decomposition
vii. Body fluids seep into the soil and insects in the soil
leave very quickly; other insects that like body fluid will
take their place
d. Decay Stage
i. Begins when the skin of corpse begins to crack open
as maggots feed on the skin and gases escape the
body
ii. Body loses bloated appearance
iii. Body emits a foul dead body odor
iv. Numbers and types of insects increase on the body
v. More and more beetles arrive and quickly remove the
flesh from the body
vi. As flesh is consumed by beetles, flies begin to leave
and most of maggots have hatched into flies and left
e. Post Decay Stage
i. Not much left of body except for home, cartilage, skin
and hair
ii. Different types of beetles come and replace those that
have left
iii. Many different types of “mites” (very small insects)
begin to inhabit the soil under the body
iv. These feed on by-products of body decomposition and
other insects that feed on the body
f. Skeletal Stage
i. Only bones and hair are left
ii. No more insects on the skeleton except for bugs that
normally inhabit the region
7. Other things entomology can tell us
a. Body disturbance
b. Presence and position of wounds
c. Linking suspect to scene
d. Drugs
e. Human and animal neglect or abuse
f. Wild life crimes
8. Challenges to Forensic Entomology
a. Temperature
b. Season
c. Exclusion: freezing, burial, or wrapping a body
9. How to become one
a. Like bugs
b. BS in Biology
c. Background in Chemistry and Physics
d. Ph.D. in entomology
e. Work generally in entomology before working on criminal
cases
f. Take continuing education courses in field
g. Get certified by American Board of Forensic Entomology