Forensic Entomology

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Forensic Entomology

• Notes on page 79

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What is Forensic Entomology?

• Applying the study of insect life cycle to
  estimating time of death
• Flies and beetles follow a life cycle that allow
  scientists to estimate how long a body has been
  deceased

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Life Cycle of the Fly
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The egg

• Shortly after death, a mature fly will lay eggs
  on the decomposing flesh
• Will typically lay eggs in moist, warm areas
• Mouth, eyes, ears, anus, wounds
• Will remain 8 hours
• Approximately 2 mm in length

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Larval stages

• Also called instar 1, 2 and 3
• Have black mouth hooks
• Will have spiracle slits near anus
• Instar 1 1 spiracle slit 5 mm in length
• Instar 2 2 spiracle slits 10 mm in length
• Instar 3 3 spiracle slits 17 mm in length
• Crop visible in 2nd instar stage covered by fat
  deposits in 3rd instar stage

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Maggots
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Pupa stages

• After 3rd instar maggots have matured, they will
  crawl away from body to a dry area
• Become immobile, do not eat, changes to a dark
  brown color, pupa case is hard
• Can stay in pupa cases for 10-16 days

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Adult flies

• Adult fly matures in approximately 21-24 days
• They will be alive for several weeks
• Not able to fly in first couple of hours

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Beetles

• Beetle larva differ from maggots in that they
  have 3 pairs of legs
• Arrive on body after flies lay eggs
• Come to feed on the maggots

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Question

• Answer this question on page 78
• Explain how flies and maggots are used to help
  estimate the time since death of a decomposing
  body