Forensic Entomology Flashcards
What is Forensic Entomology?
- It is the study of insects found on corpses or found around crime scenes in the interest of forensic science.
What is the most common insect associated with forensic entomology?
- Blowflies and they arrive within minutes of death.
What are the five stages of decomposition?
- Fresh stage
- Bloat stage
- Active decay
- Advanced decay
- Skeletonization
What happens in the fresh stage of decomposition?
- Once death has occurred, blowflies are the first insects that are attracted to the corpse.
What happens in the
bloat stage of decomposition?
- As the body starts to swell and gases are released from the body, this attracts blowflies.
- As blowflies will lay eggs this will attract predators.
What happens in the active stage of decomposition?
- The skin sloughs off the body and putrefaction occurs.
- When putrefaction is happening butanoic and casein acid are produced and this attracts more insects to the body.
What is putrefaction?
- The decay of organs and internal material.
What happens in the advanced active stage of decomposition?
- Majority of the soft tissue is lost.
- The blowfly larvae s absent and the only insects that remain are beetles.
What are the three factors that can estimate the time of death from species composition?
- Temperature
- Time of year
- The species found on the corpse.
What is the first stage of the blowfly life cycle?
- The female blowfly lays her eggs under the body via natural openings.
- The 1st instar larvae hatch and they start feeding on tissues and bacteria.
What does larvae mean?
- An immature form of an insect.
What does instar mean?
- The developmental stage of an insect.
- Occurs each moult until the insect reaches sexual maturity.
What is the second stage of the blowfly life cycle?
- After 24-48 hours the larvae moult to the 2nd instar.
- The 3rd instar occurs 24-48 hours of the 2nd instar.
- After the 3rd instar occurs the blowflies have reached their optimal size and they move away from the body.
What is the third stage of the blowfly life cycle?
- The blowflie larvae burrow into the soils and become a pupates (immature insect before becoming an adult).
- The larvae reach adult hood and the body hardens and wings expand.
What is the fourth stage of the blowfly life cycle?
- The adult blowfly flies away to find a source of nectar/ faeces.
- Adult flies live for several weeks.
- The temperature hugely affects their lifecycle.
What is a pupa?
- It is an insect in its active immature form between larvae and adult.
How can the minimum time since death be calculated with flies?
- You compare a ‘field’ maggot with a ‘lab’ maggot by looking at their stages of development.
- Temperature is a major factor that needs to be taken into consideration.
- We can overcome this issue as we know the time to development increase by temperature.
What is the calculation for the minimum time since death?
- Accumulated degree/ days= time taken to reach stage x (temperature-base temperature)
What is myiasis?
- It is a parasitic infection of fly larvae on human tissue.
- Infest wounds or live on the surface of the body.
- Can lead to septicaemia and this is infection of the blood.
What is the relationships between invertebrates and geographical distribution?
- Many invertebrates have restricted geographical distribution.
-The presence of invertebrates can determine the past history of a person or object.
