Collection at Autopsy and from the Body

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.

Once the body is on the examination table, the entomologist documents 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.

1. Photograph each mass from a standardised distance (30 cm is workable) with a scale rule and the case number label in frame. Record the body region in the photograph label.
2. Estimate mass volume by its surface area and depth. A rough category (small: less than a golf ball, medium, large: larger than a fist) is acceptable if a precise measurement is not possible without disturbing the mass.
3. Insert a probe thermometer into the core of each mass and record the reading. In the mortuary the ambient temperature is controlled and typically lower than the scene, so mass temperatures will be falling. Record the time alongside the temperature.
4. Note the dominant instar by visual inspection: first-instar larvae are thread-thin and white; second-instar are larger and show a more distinct anterior spiracle; third-instar are the largest and often actively mobile.

After documentation, collection proceeds from the head to the lower extremities. Using a different pair of forceps between zones, or rinsing between uses, prevents cross-contamination. Each zone's sample goes into a separately labelled vial.

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.

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 puparium found inside a trouser pocket, where larval access would have been restricted, indicates the body remained in a particular position long enough for a larva to wander inside and pupate.

During the internal phase of the autopsy, the pathologist opens the cranium and thoracoabdominal cavity. The entomologist must be present, or at least alerted, before each cavity is opened: insects inside are inaccessible without the pathologist's assistance and will be disrupted if collection is not coordinated in advance.

Larvae inside the skull may have entered through the orbital sockets, the nose, or a cranial injury. They are often third-instar and may be more developed than surface larvae if the cranial vault provided a warm, sheltered 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.

At the end of collection, the entomologist should hold a complete log of every vial and rearing container, each uniquely numbered, recording: case and scene reference, date and time of collection, body zone, instar present, temperature, 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, covering anything the insects suggest about colonisation timing or PMI, ensures that the pathologist's report and the entomological report rest on consistent assumptions.