Forensic Entomology in Medico-...

Forensic Entomology in Medico-Legal Investigation | Dr. Denise Gemmellaro

Expert Profile

Dr. Denise Gemmellaro is currently working as Assistant Professor in the School of Natural and Applied Science, Kean University, Union and Hillside, New Jersey. She excels and having outstanding experience in her academic qualifications. She has been working as a writer, editor proofreader, and translator from Italian into English and from English into Italian. She has experience with an immense interest in forensic entomology, decomposition ecology, Diptera biodiversity, insect ecology, etc. She has had such wide research experience for many years and has examined different species of insects. She was certified as a Member of the American Board of Forensic Entomology (ABFE). She has numerous publications under her name with a versatile intellectual approach. She has also been actively involved and conducted numerous training and workshops. She has also actively presented various presentations at conferences. 


Dr. Denise has precisely talked about the use of arthropods in medico-legal investigations by giving full coverage to the topic as when, where, and how the insects could help forensic investigators to identify the post mortem interval and several other leads to the investigation. Further, the pictorial illustration of the actual corpse showing various stages of decomposition gives an appropriate entomological investigative perspective to the learner.


As we all are aware of the fact that when any murder or crime happens at a place, then we usually call the forensic team to investigate the crime scene and to solve the facts of how the crime has happened. Different forensic investigators like investigating officers, forensic pathologists, and other team members play a very significant role in investigating the crime scene. Similarly, forensic entomologist also plays a very important role in determining the crime-related facts. To understand this, we need to first understand what is  Forensic entomology.

What is Forensic Entomology?

Entomology is the scientific study of insects of different species and Forensic entomology is the study of arthropods, insects, and other species that are associated with crimes and any type of legal issues. In short, insects + legal matter = forensic entomology. There are 3 main areas in which entomology can be categorized.

Figure 1- Areas of Entomology

1. Stored product entomology involves the investigation of the unwanted presence of insects in the food products after the food is being harvested. For example, tiny beetle was found in a bag of chips.

2. Urban entomology involves the investigation of any type of insect activity in a man-made structure. The man-made structure could be of anything. For example, Bed, hospital bed, jar, and many more. 

3. Medico-legal entomology is the most important one for the investigation of crime. This involves the investigation of insects that mostly attracts the decomposition of a dead body. Insects are very important for investigation in a crime scene because they can give a lot of information about the crime that has happened.

If we talk about the insects, then these tiny-looking species are spy agents in solving crimes who tell their secrets to forensic entomologists only. The insects can be used in various aspects in the crime scene investigation. They can determine the post-mortem interval of a dead body. Now, you might be wondering what this post-mortem interval is? So, the post-mortem interval is the time difference between the deaths occurred of the body to the time when the body has been discovered.
Use of scientific study of insects can determine in solving the 3 major and very important questions of a crime that comes in everyone’s mind, i.e.

Where did the crime happen?
When did the crime happen?
How did the crime happen?

Let’s understand these interesting topics one by one 

Where did the crime happen?

Forensic entomologists do study and observe the natural habitats of the insects of different species. Depending on the habitat, they can understand where the crime has happened. A case study was discussed by Dr. Denise Gemmellaro, named ‘Urban v/s Rural’ in Hawaii. In this case, one dead body of a person was found in the woods and maggots were feeding all over the dead body. After carefully examining the habitat of the maggots by the experts, the maggots were found to be from a different location from where the dead body was found. This indicates that the dead body has been moved from one location to another. The insects that were present there were more likely to be present in warmer areas.

When did the crime happen?

The next question about which everyone wants to have an answer is when the crime has happened? To answer this question Dr. Deinse explains the determination of time since death from the insect’s developmental stages. As the insects are the first ones to reach a dead body and then they start taking the body for the source of their nourishment, so by examining the developmental stage of the insect we can determine up to a great instance that how much time may have been passed since the death of the person.
 To study the time since the death of the dead body, forensic entomologist studies the age of the insect development. Blowflies are being the best indicators in this intake which are taken into consideration by the forensic entomologist. The Blowflies belong to the Order Diptera and family Calliphoridae. The life cycle of Blowfly is broken up into distinct stages such as the egg, the larvae, the pupa, and the adult.

Figure 2- Life Cycle of Blowfly


The blowflies do not lay individual eggs instead an individual blowfly will lay in clusters of at least 250-300 eggs so you can see the massive colonization over the body because there would be a lot and lots of bow flies present at the time. The location where the eggs can be seen are the natural orifices such as the nose, eyes, neck, mouth, genital area because these areas are the most suitable area for protection and moisture.


The eggs then move to the second developmental stage which is known as larva and in this stage the larvae further move into 3 instars, which are 1st instar larvae, 2nd instar larvae, and the 3rd instar larvae. the purpose of the larval stage is to feed, so they will consume the body very quickly depending on the many factors such as the no. temperature and so on


Once the larvae have done with eating, they move away from the body particularly for a drier area for the 3rsd stage of their life cycle which is known as a pupa. At this stage, they don’t need any food and moisture anymore. The pulpal stage is the stage of metamorphosis in which the larvae first enclose themselves in a hard papal cover and inside which they undergo metamorphosis to bring out as an adult fly

Adult fly

After the 3rd stage, the adult blowfly will emerge out from the pupal cover. And the cycle repeats again. Typically this cycle complete in 2 to 3 weeks depending on the species
So if know the developmental stages and can calculate the time which an insect may have taken to move from one stage to another depending on the temperature and geographical area, we can use this information as an instrument to access that when the death of the person may have occurred

How did the crime happen?

The next question which comes to our mind is that how that particular crime has happened? And even in this question, the insects have been proved as a beneficial tool to get an answer because we know certain behavior of the insects. To understand this fact let’s have a look at picture 1 below. A case that was discussed by Dr. Denise Gemmellaro happened in the Southern United States. On seeing closely, massive colonization of insect was found on the forearm which has been skeletonized by the insect activity. As we know the insect’s behavior that they prefer to colonized on natural orifices and the forearm is not the area where the insects prefer to colonize naturally. It was not a natural orifice then why the insects have chosen this area to lay eggs? The answer is simple for the entomologist who knows that the insects prefer the natural orifices because of the nourishment and the moisture so it can be inferred that in the forearm there must have been a wound due to which there have been blood and moisture which attracts the insects to lay an egg on that particular place. Now it’s a known fact that the wound on the forearm is generally the defense would which have been inflicted when the victim was protecting or defending himself from the attacker, so by seeing colonization of insect egg on an unnatural area we can infer up to that the person may have been attacked by the offender and it may be a case of homicide.

Figure 3- Colonization on Forearm

Stages of Decomposition
Apart from the analysis of developmental stages of insects Dr. Denise Gemmellaro advises studying the human decomposition stages as well. After the death of a person, the body starts decomposing in different stages. The decomposition of the body involves physical and chemical changes in surroundings. The decomposition of an organism can be divided into different stages: fresh, bloated, active decay, advanced decay, and dry/skeletal. Each decomposition stage occurs at a particular time during the decomposition.

Then she explains the decomposition stages by citing the research of a very well known forensic entomologist Haskell’s 1986 research

1. Fresh Stage

 In this stage, fresh blood can be seen on the dead body. The corpse doesn’t seem to be decomposed. When the body is fresh there is no particular smell, or visual phenomenon is seen. What we see at the fresh stage is the stage of Rigor Mortis in which the body becomes stiff and the Algor Mortis where the body started to cool down until the temperature of the body reaches the temperature of the environment and then we can see the Stage of Liver Mortis, the stage of discoloration due to the pooling of blood inside the body.

Figure 4- Fresh Stage

2. Bloat Stage 

In this stage, the body becomes bloated because of the gases released by the bacteria present inside the body. The presence of blowflies, flesh flies, filth flies, yellow jackets, beetles, and cheese skippers may also be seen.

Figure 5- Bloat Stage

3. Active decay

The pressure of the gases caused by the bacteria breaks the skin and tissues and few lacerations can be observed on the abdomen and thorax area. This will cause the fluids and gases to escape from the body causing a bad odor in the surroundings. The numbers of adult flies decrease, larvae feeding on the corpse and large predatory beetles feeding on the larvae can also be observed.

Figure 6- Active Decay

4. Advanced decay

In this stage, most of the flesh is removed, In this stage, maggots develop a lot of heat around the body by their continuous movement and producing high temperature. 

Figure 7- Advanced Decay

5. Dry

In this stage, only dry remains will remain. Dry remains like leathery skin, hair, cartilage, and bones.  In some cases, small predatory beetles can also be found. Then, the body becomes skeletonized and only bones will remain at the end.

Figure 8- Dry Stage

Now let’s have a look at some of the interesting case histories that were discussed by Dr. Denise Gemmellaro-

First case

A body was found dead in the woods. The victim that was found was a female and she was shot. While performing the sketch of the crime scene, forensic entomologists have noticed that the colonization of the body was very heavy in the facial area which arouses a question why is it like that? Second important thing was that the dead person was seen alive 7 days before the body was found but the maggots around the facial area seemed to be 14 days old. After analysis of the gut content of the maggots, they have found some traces of cocaine. Cocaine is a stimulant in maggots also so they made them look bigger actually when the body was found but in reality, they were 7 days old that makes sense.

Figure 9- Maggots on Coke- Case History

Second case

A dead body of a woman was found in New Jersey, New York. There was a bad odor coming from the garage so the concerned person called the police. When police and the forensic experts arrived at the crime scene, they found that the body was wrapped in blankets and sleeping bags. When they opened the body, colonization was there on the neck. Maggots that were collected were normally active in the Southern United States which showed that species are actually moving up from another area.  

Figure 10- Newark NJ- Case History


Coming to the conclusion Denise has discussed some training and internship opportunities in forensic entomology in different countries. As this field is relatively new in academics it’s quite not easy to get the direct opportunity in some countries but in other countries where this field is advancing, there is a lot of opportunities. She also told about the workshop which she has been organizing every in new jersey for about 2 weeks in which she provide students with a lot of subject knowledge along with
Lab training
Field visit
CSI training
Scientific writing 
Forensic legal components
Multidisciplinary component 

She has also discussed the interdisciplinary application of forensic entomology in

Molecular biology

Personal Note

This session was more than just a talk. It was loaded with the extremely important piece of information along with the live experience of the speaker in different cases. She started with the definition of entomology and with every passing minute, the session has become more and more interesting by answering the where, when, and how the crime has occurred, along with the detailed explanation of decomposition stages and with a nail-biting case history. She has closed her talk with the most important discussion of carrier, training, internship, and workshop opportunities of students from all corners of the world. The session is more than this blog so to get the detailed insight direct by the speaker you can visit our YouTube Channel forensic365

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