Jump to content


Insects! Gross! A Look at Forensic Entomology

Posted by Hurrikane , 02 February 2011 · 1,884 views

Crime Murder Entomology Anthropology CSI Bugs
I have written this in the hope that it sheds a little more interest on Forensic Anthropology and Entomology. I again stress not to take anything written here as complete valid points and stress errors may occur. I am open to suggestions, changes, different interpretations etc. It is my goal to provide the best basic fundamental understanding of the subject. This was written in part for a forensic anthropology discussion I was attending, a possible expansion for a college class, and for fun. I have attempted to cite everything used within the document as well and hope that if any potential plagiarism exists, even though I doubt there actually is any, that you realize this is not to my monetary benefit and was done so with absolutely no intent to deprive the original source.

Forensic Anthropology

Forensic Entomology: A Brief Overview
Origins and Relation to Anthropology
Entomology in Forensic Cases
The Bugs
Techniques and the Law
Media Interpretation & Influence

Gil Grissom, the “Bug Man” from the hit CBS franchise CSI, is probably the closest thing that most people have ever come to forensic entomology, or even just entomology in general. Despite the flaws in forensic investigation displayed throughout the shows award-winning eleven seasons, it captured the imagination of millions of people who often religiously watched the hit-drama. Grissom’s fascination and interest in the lifecycle of insects inspired a small number of people to actually look into forensic entomology and understand its concepts in more detail than what is shown in the show. Entomology is far more complex than it is depicted in the media. It is a relatively new, misunderstood and over generalized science that has proven its value but still needs more research to improve its results outside the laboratory. In this paper, I will discuss what entomology is, how it relates to pathology, its history, how it is used, the bugs that entomologists look for to identify a post-mortem interval, media depiction, today’s uses and important cases where entomology has proved its significance.
Origins and Relation to Anthropology
What is Entomology? To fully understand entomology, it is imperative to understand not only what entomology is, but where the term came from and also a history of the subject. In a general definition, entomology comes from the Greek word entomos, "that which is cut in pieces or engraved/segmented", or “insect”. (Chapman, 60 ). Many sciences have a use for insect study, but for anthropology and forensic anthropology, entomology is “the use of the insects and their arthropod relatives that inhabit decomposing remains to aid legal investigation” (Byrd, www). “Anyone involved in death investigations quickly become aware of the connection between dead bodies and maggots” (Goff, 9). Beginning in the late 1800’s, forensic entomology was seldom practiced (Goff, 9) because the understanding of insects and their importance to forensic cases was not an accepted scientific practice in forensic investigations. However, its uses were not a new idea as the application of insect evidence to criminal investigation was practiced as early as the thirteenth century, (Goff, 10) when Chinese man Sung Tsu used the idea of insect attraction to blood and tissue to find a murderer in a small farming village (Goff, 10). Although the works of  Song Ci – a medical expert from China who looked over crime scenes during the Southern Song dynasty, Louis François Etienne Bergeret, Francesco Redi who wrote the “Experiments on the Origins of Insects” in 1668 (Bigelow, www),  Jean Pierre Mégnin - a French army entomologist whose work from the 19th century was invaluable to the success of future generations which he documented in his book “La Faune des Cadavres” (gallica, www), Eduard von Hofmann –the first leading forensic pathologists (Hofman, 12), and Hermann Reinhard – who specialized in Beetles (Goff, 34), it has only been in the last thirty-fifty years that forensic entomology has become a widely used method of forensic investigation (Goff,  25)
Entomology in Forensic Cases
Entomology is exceptionally important in forensic pathology which is estimating time of death from certain factors on a dead body. When a dead body is discovered, it is imperative for law enforcement to know a relative period of when death occurred as this can be used to look at missing-persons reports to potentially identify a victim. It is the job of the entomologist to “interpret the varied interactions between arthropods and the corpse to identify this time since death” (Goff, 25). A number of environmental factors may increase or decrease insect activity. These conditions include, but are not limited to: temperature, climate, access, clothing, pesticides, drugs, percentage body fat, and even the cause of death (uwa.edu, www).
In a regular environment, insects usually appear within a couple of hours after death but the regular timeline can be escalated by hot humid climates or slowed by cold arid climates (Class Notes). Large amounts of rain will often cause a slowing in insect activity because of the drop in temperature associated with rain while light rain in a humid environment can work as an insulator, thus increasing temperature and insect activity (Goff, 43). Insect activity is drastically sped up by warm temperatures while slowed in cold temperatures, therefore if a body is left in the sun and allowed to be heated up, then it is more likely that there will be higher insect activity than on a body left in the shade. This can also lead to a decreased development time of larvae and was proved by experiments by Bernard Greenberg and John Charles Kunich which showed  that “developmental time for maggots was significantly reduced” for rabbit carcasses in higher temperatures than those in lower temperatures (Greenberg, 56). Exposure to air can also be influential, a body that has been hanged can begin to decompose slightly quicker than a body left on the ground and can also dry out at a quicker rate. Fluids can often fall from the height to the ground and insects may accumulate below the body as well. “In this area most of the expected fauna can be found. Also, it is more likely that rove beetles and other non-flying insects will be found here instead of directly on the body. Fly maggots, initially deposited on the body, may also be found below.” (Goff, 76)
Access to the body could potentially prevent certain insects from reaching the body. If a body is submerged in water or buried, then certain insects will obviously not be found. If a body is left in a large amount of water for a substantial amount of time, then it may also cause a delay or even prevent insects from being attracted to a body as the benefits to the insects of reaching the body are not worth the potential risks, however data for this is still inconclusive (Goff, 36). While there are numerous universal  beetles and flies, many insects can only survive in certain habitats and are found within certain ranges. if a body is found in New York but has insects foreign to that region on it, then that would indicate the body has probably been moved and post-mortem interval may have been effected (Gallicia, www).
Clothing and wraps can also deter insect activity for a time. This is because there is a natural barrier preventing insects from getting to the flesh, but this does not prevent activity at areas where there is exposed skin like the face (especially the ears, eyes, nose and mouth). If a body is tightly wrapped in garments then the insects will have no way of getting through the tight wrapping (Goff, 34).
If the body has a high percentage of body fat it is much more likely to have a larger amount of insect activity as well as have increased decomposition. This is due in part to more ‘food’ for the insects as well as the body fat usually contains heat longer than regular  bodies and are therefore better breeding grounds for larvae than other bodies (Catts, 11).
Drug use also has an influence on insect activity. It has been hypothesized that traces of cocaine may increase insect development while drugs containing arsenic may slow down insect development (Campobasso, 18). Widespread pest-control chemicals may deter insect activity around bodies in fields. Natural chemicals found in certain plants can reduce insect population too, for example Caffeine, a plant-based alkaloid which stimulates the central nervous system of any creature that ingests it, protects a number of plants from insect activity as the drug over-stimulates the insects causing them to collapse, in a way over-dosing on caffeine (wisegeek, www). Drug effects on insects are still a relatively new concept and therefore it is a new addition to the study of forensic entomologists.
The Bugs
Insects are attracted to dead bodies because they can feast and lay their eggs in the body, usually in the hotter places of the body like the penis, vagina, anus, mouth, and nose (Class Notes).  
It is almost always flies that are the first insects that appear on the body because of their apparent ability to smell death up to ten miles (16 kilometers) away but this has yet to be proven by a reliable source. The Blowfly, a 10-12 millimeter metallic insect, is the most useful insect used in forensic entomology because it inhabits almost every environment and thus it, and it’s lifecycle, is the best and most universal insect to use in investigations (Class Notes).  However, it has to be noted that blowflies are not prevalent in Southern California, Arizona, New Mexico, Louisiana, Florida, or Illinois regions (Whitworth, 7). There are over 1100 species of blowflies worldwide, but they all follow a very similar pattern which is why they are used in entomological investigations across the world. For example all Blowflies lay their eggs during the day and have a gestation period of roughly eight to twenty-four hours (Class Notes). Due to the fly’s inability to lay eggs during the night, this can cause slight errors in an entomological time since death interval as insects will not be attracted until dawn despite a death during the night, potentially throwing the timeline off by a number of hours (Class Notes). Due to this problem, forensic investigators will rely on other methods to establish a time of death such as rigor mortis and algor mortis, if the body is fresh or if there is a lack of insects.
Other types of flies are also used by entomologists. Fleshflies are also a commonly used fly in investigations. Some species of flesh flies are known to lay their eggs in open wounds in mammals, hence their name. They are usually found on decaying bodies which makes them valuable in estimating a longer post-mortem interval. The Cheese fly is only attracted to bodies three to six months after death (Aluja, 32). The black soldier fly arrives at the body after 4-5 months when a large amount of decomposition has already occurred, and this is significantly important because research suggests that with the presence of the black soldier fly, the blowfly stage has already come to an end. This fly is one of few flies that will eat larvae of other species so pathologists often add at least an hour to the post-mortem interval for their presence because their eating of previous  fly species can potentially throw off the post-mortem interval.  The black soldier fly is also not attracted to burned flesh which means the pathologist would not need to worry about this environmental factor affecting the rate of decomposition (Brundage, www). “Current research into Hydrotaea spinigera has come to show that it makes up roughly seventy percent of the Muscidae found on a body that is discovered in a forest region” (Greenberg, www).
It is not only flies that will feast and lay eggs in a body. Beetles will begin to replace flies as decomposition increases because they are larger and will also eat the larvae of the flies (Class Notes). The most forensically significant beeltes are: the rove beetle, the Histler Beetle, the Carrion Beetle.
The rove beetle and the Hister Beetle are the most common beetles found in forensic investigations. There are over 46,000 species of Rove Beetles found all across the globe which makes them a prime candidate for universal research analysis. Adult Rove Beetles are commonly seen in the early stages of decomposition, feeding on larvae of all species of fly (Craig, www).
Hister Beetles are even better indicators for time since death because they are much more active in the spring and summer than any other time of the year, certain species are also more active during different times of the year, and particular species prefer the body in different stages of decomposition. Hister Beetles are more active during the night and their eggs have a short development time, this means that sometimes a body needs to be observed during different times of the day (Byrd, www). They are also much more destructive than other insects on the body . Beetle larvae are helpful when determining post-mortem time interval. Beetle larvae often reside in fly breeding resources, and they can be distinguished from fly larvae by the following: possess a hard, head capsule, often brown in color. Fly larvae lack a head capsule, instead having distinct, internal, black mouth hooks - the anterior end of their body. (Myers, www).  Understanding how long ago the eggs were laid and the time period of the developmental stages is important for determining the post-mortem interval.
Carrion Beetles present a challenge to estimated post-mortem interval because their larvae are “opportunistic predators that will feed on dipteran eggs, larvae, and on the carcass itself” (Watson, 335) By eliminating the first colonizing species Carrion Beetles can give an incorrect post-mortem interval and this makes it harder to identify the victim (Watson, 347).
Other insects apart from flies and beetles may be found on the body. Moths are often seen at the very last stages of decomposition as they lay their eggs and feed on the hair in the body. Bees, wasps and ants have also been identified on bodies but are more likely to be found preying on other insects than actually feeding on the body (O’Donnell, 323), this can be a problem as it can cause issues with determining an accurate post-mortem interval.  
Techniques and the Law
As improvements in technology have continued, new ways of identifying forensically significant data has greatly improved, especially in the study of entomology. These include mock crime scenes tests, gene and DNA expression studies, and some other new intriguing methods.
Mock crime scenes were probably the first used method of trying to identify universal post-mortem intervals as it requires just simple observation  and recording techniques. Researchers use pig carcasses as mock dead bodies and record decomposition rates on the carcass as pig skin is similar to human skin (Schloney, 402). There are five facilities across the United States collectively called Body Farms in which they study the rate of decomposition in various environments. They are funded by top universities across the nation. Bodies are donated from various places and entomological interactions with a body, if any, is studied. The data obtained from these body farms has helped in developing universal timelines for decomposition that are increasingly becoming more accurate as research continues. Some of the more accepted newer methods are Scanning Electron Microscopy, potassium staining and Mitochondrial DNA analysis. When only the eggs of the species are present, scanning electron microscopy has been developed in order to identify which species larvae are inside the eggs (Mendonça, www). Despite this fantastic tool, it is extremely expensive and requires rare pieces of technology.  A cheaper alternative to Scanning Electron Microscopy is Potassium Stating. The eggs are collected and are stained in a 1% potassium permanganate solution to dehydrate the eggs. They are then viewed under a microscope and the measurements and observations are compared to standards of forensically important species and used to determine the proper species (Sukontason, 320). The most recent breakthrough in entomology investigation techniques is the use of mitochondrial DNA. In 2001, Jeffrey Wells and Felix Sperling found a way to use mitochondrial DNA to differentiate between different species of flies and this is useful when working on determining the identity of specimens that do not have distinctive morphological characteristics at certain life stages (Wells, 103).
For these methods to be accepted in court, they must undergo some specific tests. The Frye “General Acceptability” test is the first test that data must undergo. The method of retrieving the data, and the conclusions from the data, must be accepted by the general scientific community and it is this test that often disqualifies evidence from a courtroom (Greenberg, www). The Daubert relevancy and reliability requirement is the second part in which it is not the evidence that is clarified for the courts but the scientist who performed the tests/research.It is up to the judges discretion if the data present is allowed to be shown in courts (Greenberg, www). Some judges have admitted an aversion to scientific evidence because the jury often takes the data shown as fact and does not make its own interpretations on the data. One way that judges have attempted to admit scientific evidence is only if it is presented with an expert witness as well as presenting data in its “raw form,” which allows the jurors to make their own conclusions from the data presented (Greenberg, www).
In Daubert v. Merrell Dow Pharmaceuticals, the Supreme Court determined a standard for admitting expert testimony in courts (Gottesman, 12). Since entomology is such small field and few people understand it, it is imperative that an entomologist come and discuss their findings to the court. This is made difficult because courts ban repulsive information or photographs, and insects feeding on a corpse probably falls in this category.
All data to be presented in court is submitted in a Case Study Final Report (Greenberg, www). It contains all entomological data relevant to the case including initial contact notes, death scene case study form, scene case study form, autopsy report, local weather reports, specimen identification and the chain of custody chart. All evidence gathered must be carefully gathered, collected and labeled to ensure a proper chain of evidence as well otherwise the entomology timeline may be disrupted and can be dismissed in courts (Class Notes). Since forensic entomology is not a precise science, it is considered “overzealous” to announce full certainty on the findings (Greenberg, www). This is best shown in a court case in 2002 involving forensic entomology when self employed engineer David Westerfield murdered a seven year old boy. Four entomologists Dr. Robert D. Hall, Dr. David Faulkner, Dr. Neal Haskell and  Dr. M. Lee Goff were all asked to analyze the data .Dr. M. Lee Goff claimed the body was colonized by insects much earlier than the other entomologists believed (Dillon, www). This could have meant that David Westerfield could have been cleared of the charges.
Media Interpretation and Influence
Entomology has had a serious increase in attention because of shows like CSI and Bones. It has lead to the popular term ‘CSI Effect’ where people expect all aspects of forensic investigation to be as conclusive in its findings as in these shows. The shows often leave a false trail in that people expect answers to be figured out within minutes of the body being found but it could take days to fully understand all the activity happening on a decomposing body. This has lead to increase research funding and testing of hypothesis’. Increased funding has allowed some entomologists to be able to identify a victim’s time of death to the exact day “even if the person has been dead for a matter of weeks.” (Sukontason, www) Popular criminal investigations shows have also lead to “smarter criminals” because people have a greater understanding of forensic investigation and are now able to identify where they can hide their crimes or leave false evidence.
Entomology continues to become a well-rounded and established tool in the scientific community in determining post-mortem interval and helping in legal investigations. As new data develops, it will constantly adapt and change to allow better answers.  Hit shows like CSI have intrigued many people and have helped establish a public understanding and funding.

Works Cited
Aluja, Martin and Norrbom, Allen. Fruit Flies (Tephritidae). CRC Press. 1999
Bigelow, Mab (translation and notes). ed. Experiments on the Generation of Insects. Francesco Redi of Arezzo ]. Chicago: Open Court. 1968
Campobasso, Carlo P., Giancarlo D. Vella, and Francesco Introna. "Factors Affecting Decomposition and Diptera Colonization." Forensic Science International, Science Direct. Texas A&M University, College Station, 2001
Catts, E. P. and N. H. Haskell, eds. “Entomology & Death: A Procedural Guide.” Joyce's Print Shop, Inc. 1990.
Chapman, A. D.” Numbers of living species in Australia and the World” Canberra: Australian Biological Resources Study. 2006
P. C. Craig. "The behavior and distribution of the intertidal sand beetle, Thinopinus pictus (Coleoptera: Staphylinidae)". Ecology 51 1970
Goff, M. L. “A Fly for the Prosecution” Cambridge, Massachusetts: Harvard University Press, 2000.
Greenberg, Bernard, and John C. Kunich. “Entomology and the Law.” United Kingdom: Cambridge University Press, www 2002.
Mendonça, Paloma Martins. "Identification of fly eggs using scanning electron microscopy for forensic investigations." 2008. Micron Publishing, New York. 13 March 2008
O'Donnell, Sean . “Annual Review of Entomology: Reproductive Caste Determination In Eusocial Wasps (Hymenoptera: Vespidae)”. 1998
Schoenly, Kenneth G. “Recreating Death's Acre in the School Yard: Using Pig Carcasses as Model" American Biology Teacher 2008
Watson, E.J. and C.E. Carlton. “Succession of Forensically Significant Carrion Beetle Larvae on Large Carcasses (Coleoptera: Silphidae).” Southeastern Naturalist. 2005.
Wells, D. and Sperling Felix A. H. “DNA-based identification of forensically important Chrysomyinae (Diptera: Calliphoridae)” Forensic Science International Volume 120, Issues 1-215 August 2001 110-115 . 3 March 2008  
Whitworth, Terry. “Keys to Genera and Species of Blow Flies of America North of Mexico." Proceedings of the Entomological Society of Washington 2006

Internet Sources w/out Books
Faigman, David L. (2002). "Is Science Different for Lawyers?". Science 297 (5580): N/A http://animaldiversi...Histeridae.html
Gottesman, Michael. "Admissibility of Expert Testimony After Daubert: The "Prestige" Factor", 43 Emory L.J. 867, 867 (1994). Retrieved on 2009-01-13
Myers, P., R. Espinosa, and C. S. Parr. "Family Histeridae." Animal Diversity Web. 1998. University of Michigan Museum of Zoology. 22 Mar. 2009
Sukontason et al., K; Sukontason, KL; Piangjai, S; Boonchu, N; Kurahashi, H; Hope, M; Olson, JK (July 2004). "Identification of Forensically Important Fly Eggs Using A Potassium Permanganate Staining Technique".  15
"Forensic entomology: use of insects to help solve crimes". Uwa.edu.au. 20 March 2008.

I made a small article on my site about the Body Farm its neet how much science has played a role in solving crimes.

Nice article
  • Report

Caesar, on 02 February 2011 - 02:53 PM, said:

I made a small article on my site about the Body Farm its neet how much science has played a role in solving crimes.

Nice article

I went to school in Nashville, but a few of my anthropology professors did a fair amount of research there, it seems.
  • Report

Recent Comments

0 user(s) viewing

0 members, 0 guests, 0 anonymous users


Latest Visitors

  • Photo
    09 Apr 2011 - 06:42
  • Photo
    24 Mar 2011 - 20:54
  • Photo
    06 Feb 2011 - 20:23
  • Photo
    vampyre rayvyn
    05 Feb 2011 - 02:42
  • Photo
    04 Feb 2011 - 22:56