In a thick wooded area, a dead body lies. Within 5 to 10 minutes, a slew of tiny winged visitors –blow flies – are the first on the scene.
As minutes turn to hours, and turn to days, weeks and months, the insect population will change with the passage of time. Flies, beetles and mites will come and go. Exactly which insects infest a decaying body is dependent on the conditions surrounding it, including the temperature and climate. Some insects will come to feed on the decomposing corpse, and others will come to lay eggs/larvae.
When a suspicious death occurs, insect activity on a corpse can provide valuable information to crime scene investigators about the post mortem interval. PMI is the estimated time that has elapsed since a person has died.
Forensic experts will collect insect samples from the crime scene to take back to the lab for further examination. They can compare their findings with databases detailing insect populations at different stages of development and under different temperatures to help determine PMI.
Read the full, original story: How insects and microbes reveal crime scene clues