Application of Entomology in Some Medicolegal Issues

Research Article

Austin J Forensic Sci Criminol. 2015; 2(4): 1036.

Application of Entomology in Some Medicolegal Issues

El-Mehy I¹, Sief A², Soliman E¹, Hassan NA¹* and Alrouf TA¹

¹Department of Forensic Medicine, Tanta University, Egypt

²Department of Entomology, Tanta University, Egypt

*Corresponding author: Neven Ahmed Hassan, Department of Forensic Medicine and Clinical Toxicology, Tanta University, Egypt

Received: June 29, 2015; Accepted: August 06, 2015; Published: August 09, 2015


As the application of the forensic entomology has been strongly criticized for years, the present study was carried out on fifteen cases representing all putrefied cases in different seasons and habitats with larval infestation referred to the Forensic Medicine Directorate in Middle Delta. The aim of the present study was to identify and record the different species of insects that are frequently associated with human corpses to establish data base for the potential use of insects as postmortem interval indicators.

The maximum number of cases was in the age group 10-20 years, and the least number was encountered in the age group less than 10 years and over 50 years.

A relatively larger number of victims (73%) were males while female corpses were (27%) in this study. Nine of the reported cases (60%) were exposed, while, the other six cases were equally distributed between aquatic locations and burial (20% for each).

The maggots recovered from the fifteen decomposing human remains belong to family Calliphoridae and Sarcophagidae (Diptera).

The blow fly Chrysomya albiceps was the most common species invading nine cases (60%), followed by Sarcophagidae family (four cases with a percentage of 26.7%). The least number was Psychoda and Lucilia sericata which infested only one case for each (6.7%).

This study revealed that, Chrysomya albiceps was found to be a highly indicative species to corpses found in urban (6 cases) and rural (3 cases) areas representing 67% and 33% on sequence during the warmer seasons. While both Sarchophagidae and Dermistidae were equal in both urban and rural areas. Lucilia sericata and Psychoda species were only present in rural areas in this study.

In the present study Chrysomya albiceps was attracted to corpses in spring (5 cases), summer (2 cases) and winter (2 cases). Sarcophaga species larvae were infesting dead bodies in both spring (3 cases) and fall (1 case) representing 75% and 25% respectively. Luicilia sericata larvae were collected from 1 case in winter. Psychoda species and Dermestidae larvae were collected from cases in spring only.

In the present study, 3 cases were found to be of interest to forensic entomology. The first case concerned a corpse of young female killed by smothering, the second was exhumated for autopsy and the third one was partially submersed and killed by strangulation and found near a water canal coast. The implications for estimation of postmortem interval by entomological methods were discussed.

The results of this study demonstrated the usefulness of testing larvae associated with decomposed remains for toxicological analyses in cases number 12 & 14 as the cause of death was carbamate and organophosphorus toxicity respectively.

This study concluded that, in death cases where insects are associated with the remains, it can be used for detection of postmortem interval and the cause of death in some cases. The forensic entomologist should cooperate with the forensic pathologist; from the visual observations of the cadaver in the scene, through the collection of insects and temperature data up to the final report with the interpretation of entomological and other biological evidence.

Keywords: Entomology; Chrysoma albiceps; Sarchophagidae; Dermistidae; Lucilia sericata


Dead bodies undergo a variety of changes, which eventually return the tissue components to the food chain. These changes are brought about by chemical (mostly enzymatic) processes, bacterial and fungal attack and predation by many varieties of animal life, from tigers to bluebottle [1].

The sequence of putrefactive changes can be divided into four stages or phases (discoloration, bloating, liquefaction and advanced decay or skeletonization). These phases are markers for diagnostic purposes indicating time elapsed since death [2].

Insects are extremely abundant and ubiquitous organisms. Since arthropods are the largest and most important biological group on earth, they can be found in a wide variety of locations including crime scenes [3]. They are attracted to natural orifices in particular, the facial orifices to feed and lay eggs but, when wounds present, they are usually more attractive. So, insects can be used to determine presence, position, and patterns of wounds [4].

Forensic entomology is based on the analysis of the insects and other invertebrates, which sequentially colonized a corpse as decomposition progresses [5,6].

Entomo-toxicology is a relatively new branch of forensic entomology. The potential use of insects for detecting drugs and other toxins in decomposing tissues has been widely demonstrated in death investigations [7].

Entomologists with forensic experience can deduce minimum or probable times of death from the stage of development of blowfly maggots and other time-related insect colonizers. Hundreds of arthropod species are attracted by corpses, primarily flies (Diptera), beetles (Coleoptera), and their larvae, and also mites, isopods, opiliones and nematodes [8]. These insects feed, live, or breed in and on the corpse, depending on their biological preferences and the state of decomposition [3].

Basic research and advanced application of forensic entomology in the US, Russia , Canada , France and Japan as well as casework in other countries like England and India has opened the way to routine casework. Researchers worldwide use entomology in criminal investigations including murder and other high profile cases [3]. Forensic entomology has been used and accepted in courts around the world and gaining international recognition [9].

Facts are not always available from corpses when they are recovered, so the aim of this study is to 1-suggest a protocol for proper collection of specimens for the entomological study, 2- identify and record the larvae recovered from some cadavers in some governorates in Egypt (Elmahala Alkobra, Tanta, Kafr Alzayat, Zefta and Elsanta cities (Gharbia governorate), Kafr Elsheikh city (Kafr Elsheikh governorate) and Shebin Elkom city (Monofia governorate), 3-justify the role of the entomological study of these larvae in the estimation pf postmortem interval as well as a tool to answer some medicolegal questions.

Subjects and Methods

This study was carried out on 15 human putrefied corpses which were found in Middle Delta of Egypt during the period from the first of February 2004 up to the end of January 2006 (24 months). Putrefied corpses in this study referred to the Forensic Medicine directorate in Middle Delta, Ministry of Justice. These corpses were collected from Elmahala Alkobra, Tanta, Kafr Alzayat, Zefta and Elsanta cities (Gharbia governorate), Kafr Elsheikh city (Kafr Elsheikh governorate) and Shebin Elkom city (Monofia governorate).

Sociodemographic data were collected for each corpse as regard age, sex and residence.

Suggested protocol for the proper collection of specimens needed for the entomological study:

1-All data about the condition in which the corpse was found should be as regards environment, the ambient temperature, and nature of the locus in terms of vegetations, trees and undergrowth if outdoors.

2-Maggots if present should be placed live in a tube and if there is a delay in transit to the entomological labs, a fragment of meat should be included for food.

3-Adult flies and eggs should be collected without preservatives.

4-Some pupae, empty pupa cases and eggs should be sent for fixation.

5-Different species of insects on the body should be placed in separate tubes especially if alive.

6-All samples should be labeled or numbered according to the location on the corpse.

7- If outdoors, samples of the soil is collected.

According to Dadour et al. [10] larvae were collected from the bodies either in scene of death or in the mortuary as follows:

The larvae were collected from different parts of the body, natural orifices (such as mouth and nose), or wounds and soil under the corpses or near them. The larvae from each corpse were placed directly into 75% ethyl alcohol. The largest larvae were actively searched for and collected. Representative sample of 50-60 larvae was collected at the autopsy from the maggot mass in each case by a Soft-touch forceps which are useful for the collection of these larvae without damage and preserved immediately in plastic specimen containers. The samples were transported to the Department of Zoology, Entomological Lab, Faculty of science, Tanta University. The collected samples were labeled for further identification.

Morphological examination in the lab

The larvae collected in this study were placed in an aqueous solution of 10% Potassium Hydroxide (KOH) at room temperature for several days. The specimens were then washed in 75% ethyl alcohol for 10 to 15 minutes. While the maggots were in the alcohol, each one was pierced with a sharp pin (on one side) and then flattens it with a small spatula. This was to remove the remains of the body contents and to facilitate the replacement of liquids within the body cavity, in this and succeeding steps. The specimens were transferred to absolute alcohol (100%) for 10 to 15 minutes to dehydrate the specimen. Thereafter the specimens were transferred to xylene and left there overnight. The cleared specimens were placed into a mixture of xylene and canada balsam. Each maggot was mounted separately in the middle of a standard microscope slide. A large drop of canada balsam was dropped in the middle of the slide. Then the maggot was placed carefully on the Canada balsam, and care was given to place each larva on its lateral side. This position is ideal for examining the mouth hooks and anterior spiracles. A cover slip was placed over the specimen. The slides were placed on a slide-dryer. The slides were left to dry in an oven at 40°C for about two weeks. Reports describing the condition of the body when found and detailed autopsy procedures and results also were reviewed. Identifying the right species and instar was done relatively easy based on mouthparts and morphology of the posterior spiracles .Identification was made with a stereomicroscope [11].

Toxicological analysis

Raw samples of larvae were subjected to toxicological examinations by the chemical labs of forensic medicine administration using gas chromatography mass spectrum. The extraction process for samples consists of a series of operating steps according to Clarke [12].

According to Niessen [13] the mass spectrum is used to identify chemicals based on their structure.

Larvae collected from the corpses subjected to identification as regards, species, instar or stage of development, the habitat where the remains were found, expected age, season of discovery and results of toxicological examinations.

Post mortem interval: Estimation was based on comparison of data from autopsy reports (rate of decay), local environmental conditions (temperature, humidity, rainfall) and developmental times for the immature stages of each species of local arthropod and succession patterns using the schedules.

Statistical analysis

The collected data was organized, tabulated and statistically analyzed using SPSS software statistical computer package version 12. For age, the range, mean and standard deviation were calculated. For other variables, the number and percent distribution was calculated. Fisher exact test was used as a test of significance. Significance was adopted at P<0.05.


The present study was carried out on fifteen cases representing all putrefied cases with larval infestation referred to the Forensic Medicine Departments in Middle Delta (Gharbia, Menoufia and Kafr Elsheikh), Ministry of Justice, during the period from the first of February 2004 to the end of January 2006 (24 months).

The corpses were found exposed, buried or in aquatic scene.

The sociodemographic data of the studied cases were observed in Table 1. The age of these cases range from (7-54) with a mean and SD (29.07+-14.22).