A body is discovered outdoors in summer. It is heavily infested with large white maggots of the third larval instar (L3). The maximum size of the maggots is 15 mm. The ambient average temperature over the past days was 25°C. Forensic entomologists use the concept of accumulated degree days (ADD) or degree hours to estimate the minimum postmortem interval. Which fly species is MOST commonly the first coloniser in a decomposing human body in tropical India, and whose development data are used for such calculations?

• A Sarcophaga haemorrhoidalis (flesh fly)
• B Lucilia sericata (common green bottle fly)
• C Calliphora vicina (common blue bottle fly)
• D Chrysomya megacephala or Chrysomya rufifacies (Oriental latrine fly) ✓

Explanation

In tropical and subtropical India, Chrysomya megacephala and Chrysomya rufifacies (Family Calliphoridae) are the primary pioneer species that colonise fresh human remains; they arrive within minutes to hours of death, lay eggs on natural body orifices, and are therefore the most useful for minimum PMI estimation. Lucilia sericata and Calliphora vicina predominate in temperate climates (Europe, UK). Sarcophaga (flesh flies) are larviparous and may compete with blowflies but are secondary colonisers. The thermal accumulation model requires species-specific temperature-development baselines (minimum threshold approximately 8–10°C for Chrysomya species).

Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.