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Forensic Entomology

Forensic Entomology Resources

Overview of Forensic Entomology

Forensic entomology can also be used to see if an insect may have caused a death, for example the driver of a car is stung by a bee while driving and crashes his car; or a piece of instrumentation on a plane, train, elevator, etc. is ruined by bugs chewing through vital components that allow that instrumentation to work properly.  By looking at the presence and life cycle of these bugs, forensic entomologist can determine time of death, cause of death, and if the corpse has been tampered with.  There are three fields of entomology: medico legal, urban, and stored-product. Medico legal entomology is where the entomologist examines the presence and development of arthropods to help in legal cases such as murder and contraband trafficking. Arthropods are vital to the Earth’s environment they are everywhere and they are an intricate part of the decomposition process of biological materials. In the urban aspect, forensic entomologists examine how insects affect people in their immediate environments (i.e. bug bites, spreading of disease, etc.). Finally in the aspect of stored-product entomology, forensic entomologists examine pests and insects that are found in foods and may assist in criminal and/or civil cases having to do with food contamination.

Death: A Biological Process

Death is commonly known as a physical shut down of the body and is determined when all of the body’s biological functions stop working.  It’s important to remember that in most cases of death, the functions of different organs in the body cease to work at different times. Throughout human history, defining the precise moment of death has been difficult and has caused much debate. Today’s medical sciences have identified a few different types of death. Brain death is defined as when brain activity ceases even if other internal organs are functioning. In the process of death, cells and tissues are broken down in different stages. First, the body starts to cool down and biological tissues start to stiffen and become hard, this process is called rigor mortis. After all of the cells in the body cease to function the body starts to decompose as bacteria in the body begins to breakdown proteins, lipids, and other organic compounds. There are five stages of human decomposition: initial decay (where the corpse is decaying internally, but looks normal to the eye), putrefaction (the corpse swells from gas producing internally, begins to smell, and flesh begins to decay), black putrefaction (body collapses as gas escapes, odor intensifies, and flesh still intact turns creamy white and exposed parts blacken), butyric fermentation (corpse begins to dry out and mold in moist areas), and dry decay (corpse is almost completely dried out, bones are exposed and the rate of decay slows dramatically).

Crime Scene Analysis and Evidence Collection

Gathering evidence at a crime seen is essential in legal investigations. For forensic entomologist, without this evidence and with out the proper evidence collecting measures, their job is meaningless. There are a few things every forensic entomologist must do as they begin to collect evidence from a crime scene. The first is to make visual observations and come up with ideas at the scene. They must then collect information about the climate of the scene (i.e. whether, precipitation, regional information, etc.). Samples of insects as well as blood must be collected then before the body is removed. Also while the body is still there they must collect samples and specimens in the area around where the body is.  Then when the body is removed they must take samples and specimens from whatever surface the body was lying on top of.  After all this material is gathered it must be taken back to a laboratory where further tests can be conducted. Finally the forensic entomologist must use the data collected to come up with a theory for what that data means as to time of death, cause of death, and corpse manipulation.

Estimating Time of Death

There are many different methods for determining time of death of a corpse. First is to take the temperature of the corpse. The body immediately begins to cool as blood ceases to pump through it. So starting with a normal body temperature and subtracting the temperature of the corpse can help in estimating time of death. Also determining how far into the rigor mortis stage the body is also reveals information. If a body has been dead for quite some time, forensic entomologists use the presence and life cycles of Calliphoridae (flies) and Coleoptera (beetles) on the body to help determine time of death. Examining the life cycle of blow flies and beetles on the body as well as the environment around the body (i.e. weather, temperature, precipitation, etc.) that might affect those insects is one of the best ways of estimating a time of death.

Within minutes of death blow flies arrive and lay sacks of about 250 eggs on the body’s orifices such as mouths, nostrils, and genitals as well as any open wounds. In the first 24 hours these eggs hatch into first stage maggots. As they feed they molt into second-stage maggots and after several hours molt into third-stage maggots. If there are a significant number of third-stage maggots feeding on the body it can cause the body’s temperature to rise.

Movement of Corpses at Crime Scenes

After the cells in a body cease to function, certain insects (flies and beetles) and bacteria find the body immediately, and begin to colonize it. The space underneath the body also attracts these bugs and others.  It is when a forensic entomologist compares the environment of where the body was found with the information from the body (i.e. stages of rigor mortis and decomposition) that they may determine if the body had been moved after death.

Determining Cause of Death

Forensic entomology can be useful in finding out the cause of death in many different ways. Over time as a body decomposes, it becomes harder and harder to test blood and urine samples or examine stomach contents for traces of poison. However, because maggots feed on the dead body, it is possible to extract that information from dissecting the maggots themselves.  Also blowflies are attracted to the body’s orifices as well as open wounds. Most blowflies will find any open wounds on the body and be concentrated in those regions.

30 Links to Forensic Entomology Resources

  • Insects in Legal Investigations - find workshops, books, literature, and other information on forensic entomology here.
  • Forensic Entomology – information primarily directed at police officers and homicide investigators so that they may better understand the basic aspects of and terms associated with forensic entomology.
  • Cleveland Museum of Natural History – overview of forensic entomology including information on insect succession and how it is used.
  • Chemistry Biology Pharmacy Information Center - a resource list of texts and images of several different types of blow flies in different stages of the life cycle.
  • Visible Proofs – Provides online activities and lesson plans for those interested in any field of forensics.
  • The Forensic Science Society – find news and information on advancements in a wide range of forensic sciences as well as cases where forensic evidence was a key component to the verdict or appeal
  • Science in School - an overview of forensic entomology and the careers possible choices in that field of science.
  • Entomology Links – a resource list of entomology information on the web from a wide range of schools and organizations.
  • NAFEA – the official website of the North American Forensic Entomology Association providing news and information on many aspects of forensic entomology.
  • About Forensic Entomology - an overview of forensic entomology is and articles on advancements in and the development of forensic entomology.
  • Amateur Entomologists’ Society – this is an overview of what the presence and development of insects at crime scenes mean.
  • Explore Forensics – overview of forensic entomology and the types of cases it is used in.
  • Ultimate Guide to Forensic Entomology - information and resources for learning about the history, subfields, and insect types of and in forensic entomology.
  • Crime & Clues - a paper on the role of entomology in forensic investigations.
  • Interview: Forensic Entomologist Lee Goff – description of what it is like to be a forensic entomologist from the point of view of a forensic entomologist.
  • ED Informatics: Forensic Entomology – a description of what forensic entomology is and it’s history dating back to the 1300s.
  • Crime Scene Creatures – an interactive online game which allows the user to pretend to be a forensic entomologist and collect evidence.
  • National Museum of Crime & Punishment – from the museum’s CSI Blog this post details the two main methods forensic entomologist use in determining a time of death.
  • Bugs, Bodies, and Crime Scene Investigation – this article (with audio option) covers what forensic entomology is, why it’s important, and how it’s evolved to determine many aspects of criminal cases.
  • Myths Busted! – from Forensic Magazine this article tries to dispel common misconceptions and myths about what it means to be a forensic entomologist and what they do.
  • Forensic Careers – a description of what a forensic entomologist is and the three major areas of this science.
  • On Maggots and Murders - an overview of forensic entomology from the perspective of Martin Hall, a forensic entomologist and expert witness in over 30 criminal cases.
  • Forensic Entomology Overview – an overview of forensic entomology including information on the different stages of rigor mortis and decomposition.
  • Forensic Entomology: Flies and Beetles - information on forensic entomology including links to more information on specific species of flies and beetles often associated with forensic entomology.
  • Forensic Biology – an article on arthropods and how they are used in forensic entomology.
  • What They Do – a career profile for a forensic entomologist.