Determining the time of death is not always possible through medical examination alone, especially when a body is discovered days after death. In such cases, forensic entomologists step in, using insects found on human remains to estimate the post-mortem interval.
One such expert is Dr Tania Ivorra, a senior lecturer at Universiti Malaya, who specialises in analysing insect activity on decomposing bodies.
When insects become forensic evidence
Forensic pathologists can usually estimate the time of death within the first 72 hours. Beyond that period, insect evidence becomes crucial. Certain insects arrive at a body in a predictable sequence, allowing scientists to estimate how long death has occurred.
“Insects can detect the smell of a dead body within minutes, long before humans can,” Dr Ivorra explains. Outdoor deaths tend to attract insects faster, while closed or air-conditioned environments may delay colonisation.
The first insects to arrive are typically flies, followed by beetles. In advanced stages of decomposition, a wider variety of insects appear.
Reading the insect life cycle
Three insect families are most commonly found on decomposing bodies: Calliphoridae, Sarcophagidae and Muscidae. These insects pass through four life stages — egg, larva, pupa and adult.
“If we find larvae, we know it’s an early stage. Pupae indicate a later stage,” Dr Ivorra says. By identifying species and developmental stages, experts provide a time range rather than an exact moment of death.
Why post-mortem reports take time
Insects collected from a body are often reared in laboratories, typically using beef liver, until they reach adulthood. This allows scientists to accurately identify the species and calculate development timelines — a process that can take weeks.
Forensic entomologists work closely with pathologists to provide courts with reliable scientific evidence, making insects an essential yet lesser-known tool in modern forensic investigations.