Practice with mock tests, learn from structured notes, and get your questions answered by a global forensic community, all in one place.
How to systematically collect insect evidence during a formal autopsy, covering body regions, clothing, the body bag, and the documentation of maggot masses before the pathologist proceeds.
Last updated:
A well-sampled crime scene does not guarantee well-collected autopsy evidence. A body that arrives at the mortuary still contains insects, and some of those insects are the most informative specimens in the case. Third-instar larvae migrating into clothing, puparia forming in body bag creases, and beetle larvae sheltering in long hair can all hold the oldest developmental stages present, setting the outer boundary of the minimum post-mortem interval. They are lost permanently if the body is cleaned before the entomologist collects.
Autopsy collection is more constrained than scene collection. The mortuary environment is controlled, the available time is limited, and the pathologist has their own workflow to maintain. The entomologist must collect systematically but quickly, working in a defined order that gathers the highest-priority samples first. They must also communicate clearly with the pathologist so that each professional gets what they need without the other's evidence being destroyed.
This topic covers autopsy collection from the moment the body arrives to the end of the internal examination. It treats body regions, clothing, and the body bag as distinct collection zones and explains which insect stages are expected in each. It also covers the documentation of maggot masses, which must happen before the standard external examination begins and cannot be recreated afterwards.
The bag that carried the body may hold older insects than the body itself.
When the body arrives in the mortuary sealed in a body bag, the bag itself must be treated as the first collection zone. Mature third-instar larvae that left the body to wander and pupate before recovery may be inside the bag rather than on the body. They are often found pressed into folds of the lining or accumulated at the lowest point of the bag.
The body bag should be opened over a clean white sheet or a plastic tray to catch any insects that fall. The inner surface of the bag, including all folds and the zip channel, should be inspected visually and with a flashlight. Any larvae, puparia, or adults found in the bag are placed in labelled containers and recorded as bag-interior collection, distinct from body surface collections.
The pathologist cannot wait indefinitely, so document maggot masses in the first five minutes.
As soon as the body is on the examination table, the entomologist should document each visible maggot mass before the pathologist begins external examination. This documentation has four components: a photograph with a scale bar, an estimate of mass volume, the dominant instar visible, and a temperature reading at the mass core.
Work head to toe, zone by zone, with separate vials for each region.
After documentation, collection proceeds systematically from the head to the lower extremities. Using a different pair of forceps (or rinsing between zones) prevents contaminating a later collection with material from an earlier one. Each zone's sample goes into a separately labelled vial.
| Body region | What to look for | Notes |
|---|---|---|
| Scalp and hair | Eggs, first-instar larvae in hair roots, puparia in dense hair | Comb hair over a white tray; small eggs are easily missed |
| Face and head openings | All larval instars, egg masses, adult remains | Highest-priority zone; nasal and oral cavities often hold oldest larvae |
| Neck and collar area | Larvae migrating down from head mass | Check under clothing collar before removal |
| Torso and wounds | Larvae in wounds, between skin folds | Document wound association before collecting |
| Ano-genital region | Independent egg masses, larvae | Separate vial; may represent a second colonisation event |
| Hands and under fingernails | Occasionally larvae or eggs if hands near face | Usually low yield but document if anything found |
| Feet and footwear interior | Wandering larvae sheltering in shoes | Remove footwear over tray; insects fall from inside |
For each zone, collect a kill-rear split as at the scene. If larvae are very scarce (fewer than ten visible), prioritise the rearing fraction for species identification and sacrifice the killed fraction. A species name without a fixed voucher is more useful than a fixed specimen of unknown species.
Insects in clothing are lost the moment garments are folded or bagged.
Before the pathologist or mortuary technician removes any garment, the entomologist should inspect each item in place. Larvae migrate under clothing as decomposition progresses, and the interior of garments, particularly waistbands, collars, and cuffs, can hold later-instar or wandering larvae at a different developmental stage from the surface masses. These represent a separate micro-environment.
Each garment should be removed individually and shaken or brushed over a clean tray. Any insects are collected from the tray, labelled with the garment name and the body zone it covered. Seams, pockets, and folded hems are particular hiding places for puparia. A single puparium found inside a trouser pocket, where access would have been restricted, can indicate that the body remained in a particular position for long enough for a larva to have wandered inside and pupated.
The pathologist opens cavities that may hold insects inaccessible from the outside.
During the internal phase of the autopsy, the pathologist opens the cranium and the thoracoabdominal cavity. The entomologist should be present or at least alerted before each cavity is opened, because insects inside these cavities are not reachable without the pathologist's assistance and will be disrupted by the opening process if collection is not coordinated.
Larvae inside the skull may have entered through the orbital sockets, the nose, or through a cranial injury. They are often third-instar and may be more advanced than surface larvae if the cranial vault provided a warm, protected microenvironment. Collect them with forceps into a separate vial labelled as internal-cranial. Similarly, any larvae found in the thorax or abdomen are labelled as internal-thoracic or internal-abdominal and kept separate, because they may represent colonisation through stab or gunshot wounds.
The mortuary is the last chance to establish the entomological record from the body.
At the end of the autopsy collection, the entomologist should have a complete log of every vial and rearing container, each uniquely numbered, with: case and scene reference, date and time of collection, body zone, instar present, temperature recorded, and collector's signature. This log forms the basis of the chain-of-custody record.
A brief verbal handover with the pathologist at the end of the session to flag anything the insects suggest, such as evidence of delayed colonisation or the presence of late-succession insects indicating a long PMI, is good practice and ensures the pathologist's report and the entomological report are consistent in their assumptions about timing.
Why must the entomologist collect from the body before the external examination begins?
Test yourself on Forensic Entomology with free, timed mocks.
Practice Forensic Entomology questionsSpotted an error in this page? Report a correction or read our editorial standards.