Summary of "How Entomologists Use Insects to Solve Crimes | WIRED"

How entomologists use insects to solve crimes

Key scientific concepts and phenomena

Forensic entomology: the use of insects that colonize human remains to estimate time since death (post-mortem interval, PMI) and provide investigative leads.
Biological clock: predictable insect development and predictable species succession on a body act as a “clock” that can be read to estimate PMI.
Temperature dependence: insect development speed depends on environmental temperature. Maggot masses can be warmer than ambient (for example, ambient 25°C vs maggot mass ~28°C), which accelerates development.
Successional waves: different insect species arrive in predictable sequences as decomposition progresses (fresh → advanced decay → mummified → skeleton), allowing PMI estimates for older remains.
Limited-access environments: containers (suitcases, trash cans, wrapped bodies) alter which insects can reach remains and produce distinct insect successions; very small flies (e.g., coffin/phorid flies) can penetrate zippers or seams.
Specific insect indicators: blowflies are early colonizers; maggot masses indicate active larval growth; dermestid/larder beetles are associated with mummification and later stages. Presence or absence of particular species indicates relative timing and conditions.

Methods and procedures

Scene sampling
- Collect insect specimens from the body and surrounding area.
- Note precise locations (on the body vs. in nearby house, container, or soil).
Species identification
- Determine which species are present to place the remains in a decomposition stage or successional wave.
Temperature recording
- Measure ambient and microenvironment temperatures, including maggot mass temperature, because development rates are temperature-dependent.
Developmental timing
- Use known life-cycle timelines (egg → larva → pupa → adult) for the identified species, adjusted for temperature, to back-calculate time of colonization and estimate PMI.
Successional analysis
- For older or highly decomposed remains, use the sequence of species present to estimate how long the body has been exposed.
Context integration
- Combine entomological findings with pathology, meteorology, and other crime-scene information to refine PMI and investigative hypotheses.
Special-case research
- Experimentally compare insect activity and decomposition in different containment and seasonal scenarios (for example, winter in suitcases vs. trash cans) to improve PMI estimates in those contexts.

Illustrative case examples

Italy case 1
- A highly decomposed female was found wrapped/covered. Maggot species and temperature measurements indicated a PMI inconsistent with a suspect’s alibi and matched communications with another person, redirecting the investigation.
Italy case 2
- A nearly mummified body showed thread-like damage from larder beetles. Successional-wave analysis suggested the body had been in place for at least about 1.5 years.
Western Australia case
- Many bodies are found in containers with limited access. Small flies can still reach remains via zippers and seams, and distinct internal successions can be used to estimate PMI. Ongoing research is investigating winter decomposition dynamics in suitcases versus trash cans.

Overall point

Forensic entomology is a holistic discipline that uses insect biology, species succession, and environmental data to provide robust PMI estimates and actionable information for investigations, helping to corroborate or refute alibis and guide inquiries.