Forensics Science Entomology

Name 3 factors that could delay fly activity on a body?

- Died at night - Lots of clothing is hard for insects to reach through - If the body is buried - If the body is under water - If the body is in a vehicle - If the body is indoors with closed doors

Name the 3 stages in Phase 1 of Decomposition and approximately how long they occur.

- Fresh (1-2 days) - Bloated (2-6 days) - Decay (5-11 days) Phase One of Decomposition is an average of 10 days.

Name the 2 stages in Phase 2 of Decomposition and approximately how long they occur.

- Post-decay (10-24 days) - Day stage (24+ days) Phase Two of Decomposition is an average of more than 2 weeks.

Describe how physical factors affect PMI.

-(Method of Burial) Bodies in caskets are hard for insects to reach due to the tight space and insects being unable to reach the body. -Temperature underground is also more constant than above ground, however, anaerobic bacteria can help with decomposing underground. -If a body is in water, there will be different types of arthropods to feed on the body than on land.

Describe how climate affects PMI.

-Different temperatures can accelerate or decrease the presence of insects (hot accelerates, cold decreases). -High winds can cover/uncover body with debris, and decrease insect activity. -Water can affect insect activity, rain can wash away insects and cause them to submerge.

Describe how chemical factors can affect PMI.

-Embalming chemicals which are poisonous to most arthropods can evaporate, but not guarantee insect activity. -Hot weather accelerates insect activity while cold weather decreases. -A body in land where insecticide was used will also affect arthropods -Drugs present in a body will be consumed by arthropods and can also affect them (stimulants such as cocaine can accelerate insect activity on the body).

What kind of evidence does the forensic investigator need to collect at the scene of death?

-Specimens on and under the body -Maggot mass temps -Temperature on and under the body -Data from weather Station/ temperature and hours of daylight -Evidence of wounds.. could look like longer PMI, but just more available surface to lay eggs -Blood trails from insect movement may look like blood splatter

phaenicia sericata

green bottle fly

Ambient temperature

temperature of surrounding air

What is entomology?

Entomology is the generalized study of insects and related arthropods (crustaceans, spiders, etc.)

What makes forensic entomology different from entomology?

Forensic entomology differs from entomology because it is the application of entomology to civil and criminal incidents. It gets put to use in criminal cases, but it also has very important applications in the civil area.

What are instars? How many stages of these are present in the cycle?

Instars are the developmental stages that fly larvae go through (maggot stages of growth). There are 3 stages of these present in a cycle.

Approximately how long does it take a fly to go through one life cycle from egg to adult?

It takes approximately 3 weeks for a fly to go through 1 life cycle, from egg to adult.

Medical Examiner

Medical doctor who figures out causes of death especially when not natural

What does diurnal mean?

Not active at night, only active during daylight hours

How many board certified forensic entomologists practice in the United States?

Only a few dozen (15)

How do animals affect PMI?

Other animals such as dogs, cats and scavengers feed on bodies. They can leave little left for insects. This makes PMI determination even harder. If a person dies indoors and hunger becomes a problem, pets will attack the body.

Many factors must be considered in estimating PMI, not just the life cycle of one fly. Name at least two.

Other factors that must be considered in estimating PMI are to obtain other corroborating evidence along with the insect data, collect & test maggots for the presence of drugs, and making note of the temperature of the body. - Drug activity (maggot tests) - Environmental conditions - Temperature of maggot mass increases decay

What is PMI?

PMI, or postmortem interval, is the time since death. In the context of forensic entomology, it is the time interval between when the body is first exposed to insects and when it is discovered

How does the forensic entomologist estimate PMI using insects?

The forensic entomologist estimates PMI using insects by looking at the time interval between when the body is first exposed to insects, to when it is discovered. From the types of insects present, their developmental stages, and degree of activity on the body, entomologists can make determinations of the PMI.

Why does the head of a body decompose first?

The head contains 7/9 of the natural body openings, and it is easier for the flies to come in and lay eggs in those openings, also the tissue is soft there

phormia regina

black blow fly

oviposition

egg deposition especially for insects

What is the major factor that determines how quickly a body will decay?

Temperature

What does a body look like in bloat stage and what causes this effect?

The body is puffed up like a balloon, and it is full of gas. This is caused by bacteria growing inside the gut and releasing waste products. Also, eggs hatching and growing maggots take up space inside the body

What type of flies come to the body after death?

The common blowfly and flesh fly are the first to come to the body after death.

What makes urban forensic entomology unique?

Urban entomology is unique because it involves the analysis of the presence of arthropods in homes, businesses, gardens, and farms. - It has to do with food products - It can look at dead animals on farms and discover if there is a pesticide used or misused - Gardens and businesses: insects in products

Climatological

Weather related

What do flies do when they light on a body?

When a fly lights (lands) on a body, the female flies lay their eggs (hundreds of them).

ADH accumulated degree hour

amount of thermal energy needed to develop from one stage of insect life cycle to another