Study on the life cycle of different blow flies helps to estimate post-mortem interval


Study on the life cycle of different blow flies helps to estimate post-mortem interval


The first insects to dwell and colonize a dead body are flies from the family Calliphoridae of the order Diptera. These insects, often referred to as blow flies, are crucial for determining the post-mortem interval (PMI), or the amount of time that has passed since a person’s death.

Introduction to Blow Flies and PMI Estimation:

  • The first insects to settle on a dead body are blow flies, which are members of the Diptera order’s Calliphoridae family.
  • They are also referred to as blow flies, and they are essential for determining the post-mortem interval (PMI), or the period since death.
  • Forensic science investigations use PMI estimates to recreate the sequence of events in criminal instances.

Seasonal Variation in Blowfly Development:

  • The development of blowflies varies seasonally, according to studies, and this is related to a variety of factors including temperature, humidity, rainfall, and genetic diversity.
  • The rate of egg laying, larval development, and pupation in blow flies can be affected by changes in various environmental conditions.

Research Details:

  • By Reject, conducted At Calicut University and the Kerala Police Academy, Paul M.P., an assistant professor, teaches in the MSc Forensic Science Program.
  • Central Kerala’s blow fly species are the main subject.
  • Eight genera and four subfamilies were used to classify 17 species of blow flies.
  • researched four species in particular: Hemipyrellia ligurriens, Chrysomya rufifacies, Chrysomya chani, and Chrysomya megacephala.

Identification of a species:

  • Identification using both morphological (physical traits) and molecular (genetic) criteria.
  • To reliably distinguish between species, molecular approaches probably utilized DNA sequencing or other genetic analysis.

Impact of Temperature and Humidity on the Life Cycle of the Blow Fly: 

  • This study looked into how temperature and humidity affect the life cycle of blow flies.
  • For all four of the examined species, it was discovered that the pre-oviposition period—the interval preceding egg laying—was much longer in the winter.
  • This implies that blowfly reproduction may be slowed down by cooler winter temperatures.

Larval Instars and the Monsoon Season: 

  • It was observed that during the monsoon season, the length and weight of larval instars—different developmental stages of larvae—were much higher.
  • Chrysomya megacephala and Chrysomya rufifacies in particular, have been observed.
  • suggests that the unique monsoon circumstances would be preferable for these species to thrive.

Regression Equation Method for PMI Estimation:

  • created a regression equation technique that proved to be the most effective way to estimate PMI using blow fly life history data.
  • This technique probably required developing a mathematical model that links the blow fly’s developmental stages to particular environmental factors.
  • provides forensic investigators with a quantitative technique to more precisely determine the time of death using blow fly data.

Significance of the study

  • The study’s importance is that it sheds light on the complex interactions between blow fly behaviour, environmental variables, and forensic applications.
  • illustrates how forensic science’s real-world challenges can be solved with the use of scientific study.
  • gives forensic specialists insightful information to help them estimate PMI more accurately.


In conclusion, this work clarifies the connections between blow fly behaviour, development, and environmental factors and shows how this information may be used for precise PMI calculation in forensic investigations.