Entomology

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  • Entomolgy
    • stages of decomposition
      • 1. Fresh
        • 2. Bloat
          • 3. Putrefaction
            • 4. Putrid Dry
              • skin and soft tissue gone
              • loss of tendons, hair, cartilage and nails
              • 19- 30 days
            • loss of skin and soft tissue
              • body starts to deflate and dry out
                • 8 – 18 days (in later summer/early autumn)
          • active decay
            • Gradual inflation of corpse occurs 4 – 6 days after death in Spring/Summer. Longer when colder.
        • cells quickly start to die
          • algor mortis
          • livor mortis
          • rigor mortis
          • cells are deprived of oxygen
    • Pigs are used when research is taken place on entomology
      • same size as human torso
      • similar digestion to humans
      • relatively hairless and skin tissue similar to humans
      • putrefaction occurs around the same time as it does in humans
    • The interpretation of entomological evidence to help resolve criminal or civil investigations
      • 3 main aspects
        • Medico-legal, urban, and stored product
    • insects found on corpses
      • Necrophagous insects – those that feed on dead flesh
      • Omnivores - Feed on both body and associated insects.
      • Predators & Parasites
      • Calliphoridae – blowflies
        • bluebottles
        • greenbottles
      • Sarcophagidae (flesh flies)
      • Muscidae (houseflies)
      • Phoridae – scuttle flies
      • Cleridae  bone beetles
      • Dermestidae   hide & skin beetles
      • Silphidae    carrion beetles
    • Estimating Time of Death (TOD)
      • The effect of temperature on the development time of insects. 
        • possible to determine an estimate EOD - earliest oviposition dates
          • from this we can estimate PMI - post mortem interval which is the time since death
            • minimum PMI estimated by insect age
            • PMI can help us to put the suspect and victim together in same time frame
        • other factors which effect development of insects
          • Night-time
          • larval crowding
          • rainfall
          • drugs/toxins
          • burning
          • access to body
          • intrinsic factors
      • refer to image to see the cycle of a blow fly
      • two main methods
        • Calculate the accumulated degree-hours/days required by larvae to reach particular stages of development
        • Kill larvae from crime scene and compare length with reference data from species-specific growth curves
    • Retrieving insects from a crime scene
      • colellct maggots from body
        • sub sample taken for estimate of PMI
          • kill maggots in boiling water
            • pour off water rinse once with 80% ethanol and then refill bottle with fresh 80% ethanol
          • kill and preserve puparia by immersion and storage in 80% ethanol
        • some frozen and some left alive
      • collect puparia from on and under the body and nearby
        • sub sample taken for estimate of PMI
          • kill maggots in boiling water
            • pour off water rinse once with 80% ethanol and then refill bottle with fresh 80% ethanol
          • kill and preserve puparia by immersion and storage in 80% ethanol
        • some frozen and some left alive

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