A body discovered outdoors in summer shows the presence of third-instar blow fly larvae (Calliphora species) approximately 1.5 cm in length. Given that the egg-to-third instar cycle takes approximately 5–7 days at 25°C, what is the minimum estimated postmortem interval?
- A 5–7 days ✓
- B 24–48 hours
- C 3–4 days
- D 10–14 days
Correct answer: A. 5–7 days
Explanation
Third-instar larvae represent the final larval stage before pupation. Reaching this stage from egg deposition requires approximately 5–7 days under optimal summer temperatures (around 25°C). The minimum PMI estimated by forensic entomology equals the time needed to reach the developmental stage observed, assuming colonisation occurred at or shortly after death. Shorter intervals apply only to first or second instar stages.
Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.
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Written and medically reviewed by the StethoPrep medical team.