A forensic entomologist uses insects found on human remains to help solve crimes. Their central task is estimating the post-mortem interval (PMI), which is the time that has passed since a person died. By studying which insects are present on a body and how far along those insects are in their life cycles, these scientists can give investigators a timeline that other forensic methods sometimes cannot.
How Insects Help Estimate Time of Death
When a person dies outdoors or in an accessible space, certain insects arrive in a predictable order. Blowflies are typically the first to reach a body, often within minutes. They lay eggs that hatch into larvae (maggots), which pass through distinct growth stages over days or weeks. Carrion beetles and other species follow later, each arriving during a specific phase of decomposition. This predictable succession of insect colonization lets a forensic entomologist work backward from what they find on a body to estimate when death occurred.
The process is not as simple as identifying a single insect. In the lab, the entomologist catalogs every species collected from the remains and determines the developmental stage of each one. A blowfly larva in its third instar (growth phase) tells a different story than one that has already formed a pupa. The entomologist also factors in environmental conditions like temperature and humidity, because heat speeds up insect development and cold slows it down. A maggot that would normally take five days to reach a certain size in warm weather might take eight days in cooler conditions. These adjustments make the PMI estimate far more precise than a rough guess based on decomposition alone.
Crime Scene and Lab Work
Forensic entomologists split their time between outdoor crime scenes and the laboratory. When police discover remains and suspect that insect evidence could be useful, they may call in a forensic entomologist to collect specimens on-site. At the scene, the entomologist gathers live and preserved insect samples from and around the body, records ambient temperature, notes the surrounding environment (shaded forest floor versus open field, for example), and documents everything with photographs.
Back in the lab, the real analysis begins. The entomologist identifies each collected species under a microscope, measures larval length and weight, and may rear live specimens to adulthood to confirm identification. Chemical tests can supplement visual analysis. All of this data feeds into the PMI calculation. The entomologist then writes a detailed report summarizing their methods, findings, and estimated timeline. That report becomes part of the case file and may later serve as evidence in court.
Beyond homicide cases, forensic entomologists sometimes help determine whether a body was moved after death. If insects found on a body are species that only live in a specific habitat, but the body was discovered somewhere else entirely, that mismatch can indicate relocation. They may also assist in cases of neglect, where the presence of certain insects on a living person can establish how long the neglect persisted.
Testifying as an Expert Witness
Forensic entomologists regularly serve as expert witnesses in criminal trials. Unlike a regular witness who can only describe what they personally saw, an expert witness is permitted to offer professional opinions based on scientific analysis. A forensic entomologist might testify that, given the insect evidence, death most likely occurred within a specific window of time.
The process starts before the trial itself. In a pretrial meeting, the entomologist sits down with the prosecuting or defense attorney to review the case findings, discuss how evidence was collected and analyzed, and go over the written report. During the trial, testimony begins with an oath and a qualification process called voir dire, where the court confirms the witness has the credentials to speak as an expert. Once qualified, the entomologist explains their analysis in plain language so the jury can follow the reasoning. Direct and cross examinations by both sides can keep an expert on the stand for hours or even multiple days in complex cases.
Education and Training
Becoming a forensic entomologist requires serious academic preparation. A bachelor’s degree in entomology, biology, or forensic science is the starting point. Purdue University, for example, offers a 120-credit bachelor’s program in insect biology with a forensic entomology concentration, designed to meet the standards of the Forensic Science Education Programs Accreditation Commission. That undergraduate work covers insect taxonomy, biology, chemistry, and crime scene investigation fundamentals.
Most practicing forensic entomologists hold a master’s degree or doctorate. Graduate programs let students specialize in medico-legal entomology, conduct original research on insect succession and decomposition, and build the depth of expertise courts expect from an expert witness. Professional certification through the American Board of Forensic Entomology (ABFE) further validates a practitioner’s qualifications. The ABFE offers both technician-level certification, which an undergraduate program can prepare you for, and full board certification for those with advanced degrees and substantial casework experience.
Where Forensic Entomologists Work
Full-time positions dedicated exclusively to forensic entomology are relatively rare. Many forensic entomologists work as university professors or researchers who consult on criminal cases as needed. Others hold positions within law enforcement crime labs, medical examiner offices, or federal agencies like the FBI. Some work in medical and diagnostic laboratories that contract with law enforcement.
Pay varies widely depending on the employer. The Bureau of Labor Statistics reported that forensic science technicians earned a median salary of about $60,590 as of 2020, with those at the 75th percentile earning roughly $79,330 and the top 10% bringing in around $100,910. Federal government positions paid significantly more, averaging approximately $120,790. On the lower end, forensic professionals in medical and diagnostic labs averaged closer to $47,060. Entry-level technicians just starting out earned under $36,630. Because many forensic entomologists hold advanced degrees and consult rather than work as salaried technicians, individual earnings can fall anywhere along this range depending on how they structure their career.
Skills That Matter on the Job
Strong identification skills are non-negotiable. A forensic entomologist needs to distinguish between hundreds of insect species at every life stage, often from degraded or partial specimens. Beyond biology, the job demands meticulous documentation habits. Every collection step, measurement, and calculation must be recorded thoroughly enough to withstand legal scrutiny months or years later.
Communication skills carry equal weight. Writing a clear, defensible report is one thing. Standing in a courtroom and explaining maggot development to a jury of non-scientists, while an opposing attorney challenges every conclusion, is another. The most effective forensic entomologists combine deep scientific knowledge with the ability to make complex findings understandable to anyone in the room.