Forensic entomology is the study of

Forensic Entomology

Forensic entomology (FE) is the study of insects as it relates to criminal or civil investigations. In criminal cases, it is used to determine postmortem interval. In civil cases, FE may be used because of the introduction of insects into a consumer product or infestation of a structure. A blowfly is an insect commonly used to aid in the determination of postmortem interval.

Research the use of the blowfly in determining postmortem interval.

Describe the stages of the life cycle of the blowfly?
How long is its life cycle (hours/days/weeks/years)?
How does temperature and moisture affect the length of the blowfly’s life cycle?
When time of death is in question, what is the process by which a forensic entomologist would collect samples?
What other information must an FE gather at the scene during the investigation?
What does the FE attempt to accomplish after gathering samples and information and bringing the items back to the laboratory?
How does the infestation of the blowfly affect the rate of decomposition?
After certain lengths of time, other insects infest the remains of a body. Provide examples of the other insects that do this. What are the time intervals in which infestation occurs?

Forensic Entomology

Forensic Entomology

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Forensic Entomology

Forensic entomology is the study of bugs in the criminal justice field in order to determine the post mortem interval (PMI). The post mortem interval refers to the time between a person dies and the body of the deceased is located. In criminal cases understanding when a person died can point to suspect or causes suspects in the case to be discarded. When a person dies bugs will be immediately be attracted to the decaying body. There are many factors that can affect the rate of decomposition affecting the PMI. The lifespan of these bugs as well as their activity provides reliable information on time of death.

The blowfly is an important insect for determining the post mortem interval. The lifecycle of the blowfly located in the decomposing body can point to how long the person has been dead. Once a person dies blow flies will immediately begin to feed of the body and lay their eggs in moist areas where their eggs will thrive. The blow fly will lay up to 250 eggs in the moist opening. The eggs will look like little small white sausages that are all laid together in clumps. These eggs will hatch within twenty four hours after being laid by the blow fly. Once the blowfly hatches it becomes larvae.

After hatching, the larvae will undergo three stages of development, lasting a combined total of 7 to 10 days (Smith, 2011).The newly hatched larvae (maggots) are in the first stage. The maggots become longer and more elongated shaped. The maggot has small hooks by the mouth that help them move or to latch on the corpse and feed. These shape and size of hooks will help determine the type of fly. Theses maggots will feed until they become second stage maggots.

A part of this process is to leave the moist area on the decaying body finding a dryer place in which to turn to pupae. This is the third stage of the maggot. The pupae are different from the other maggot forms because a harder outer shell develops. During this process the actual insect takes form within the pupae developing legs and wings. This fly is completely white until the pupae splits revealing the blow fly. When looking for pupae many are found around the body and not directly on the body due to the fact they need a dry place in which to mature. The temperature and moisture can affect the length of each stage of the blowfly development.

The number of eggs laid by blowflies can result in large masses of maggots in the body which in turn can affect the body temperature of the body. When determining time of death the temperature of the body plays an important role if the death is relatively soon before locating the body. Masses of third-stage maggots may produce heat, which can raise the temperature around them more than 10° C. (Smith, 2011). Overtime the pupae will open and a full grown blow fly will emerge from the shell.

Determining the time of death is more precise if the body is located within one month of death. New cycles of blow flies can make determining time of death more difficult. The lifecycle of the blowfly can take up to a month but be as little as ten days to complete the cycle. The blow fly is an important tool for the forensic entomologist because they lay their eggs immediately after death allowing the entomologist to make a determination of time of death. When time of death is in question samples are collected in order to be able to make the necessary calculations. The calculations are based on based on the stage the larvae are found on a body.

In order to make a determination of death the forensic scientists will collect samples of bugs at every stage from the body. The collection of these bugs is not only important to determining the post mortem interval it also provides other information to the forensic entomologist. For example if bugs collected from the body are not from the area where the body was located it points to the victim dying in another location. Bug life cans also be tested after feeding on the body to provide information on any potential substances in the body.

The bugs will be collected carefully applying standardized forensic methods. The first steps as with any crime scene is to take detailed notes about the scene locating all potential evidence including bug life on or off the body. Once the notes have been taken the evidence will be collected. The collection process begins with photographing the body and then photographing the individual bug life that will be collected. Each bug will be collected carefully and placed in an evidence envelope to be transported to the forensic lab. Each bug will be analyzed upon arrival. Once the body is moved bugs under the boy will also be collected.

Blowflies will not be the only bugs attracted to the body so not only will the blowfly, larvae, and pupae be collected but the bug life one the body. The collection process requires the forensic entomologist to pay attention to the type of environment and any special features in the environment, such as rural or urban, indoors or outdoors, wet or arid, etc (Warrington, 2010).The temperature of the body will be taken and the temperature at the scene. They will also provide specifics about where the body was located, how it was poisoned, and what direction the body was facing.

Every single detail at the scene will be used to help determine time of death. The body farm at the Quantico is used to develop information on body decaying in every possible condition and time frame in order to have more accurate information about time of death. Part of the collection process will be taking detailed notes on the scene, such as temperature, moisture levels, etc. to match the information found to the research conducted on the decomposing body and bug life. The bugs are an important part of the determination of the post mortem interval. Without the PMI determining the time of death for a decomposing body would be impossible.

The type of tools needed to collect bug life at the crime scene includes a trowel that is used to dig soil samples. The soil will contain bug life and other chemical from the decomposing body. A thermometer is brought to the scene by the entomologist in order to determine the body temperature, temperature of maggots, and temperature of surrounding environment. Secure ventilated jars are brought to the scene in order to collect live bugs. The ventilated jar will ensure the bug survives the trip to the lab. Each live bug must be placed in a separate jars include flying bugs.

Flying bugs around the body, such as blow flies, are captured with a net while tweezers re used to capture crawling bugs. Each bug and its type will yield important information about the time of death or even if the body was located at the scene originally. The forensic entomologist will bring a portable weather station to the scene in order to record weather conditions. The weather station will be left at the scene for five days to get an accurate recoding of temperature. Specimen jars are used to collect dead bugs that are also important to determining time of death.

After some time other insects will appear on the body. These insects include the fresh fly that comes after the blow fly then the coffin fly, the cheese fly, and the skin beetle. The fresh fly will appear on the body within the first three month (Welch, 2012). If the fresh fly is not present then the body has not been at the scene for three month. The coffin fly also appears within the first three months. This only provides a broad timeframe but if the cheese fly is also present then the body has been at the scene between three to six months. Skin beetles do not arrive until the body has been at the scene for over a year. This will tell the entomologist the death is not recent and the body has been at the scene for some time. Once a body has been at a scene for over a year it will take an examination of the bugs and bones to determine the post mortem interval.

References

Smith, E. (2011). Forensic Entomologists Study Insect Succession at Death Scenes. Retrieved

September 6, 2014 from https://suite.io/erika-lyn-smith/599s2hk

Warrington, D. (2010). Crime Scene Bugs. Retrieved September 6, 2014 from

http://www.forensicmag.com/articles/2010/10/crime-scene-bugs

Welch, J. (2012). How forensic science (entomology) works: blow flies, coffin bugs, carrion

beetles on a corpse. Retrieved September 6, 2014 from http://schatzie-

speaks.hubpages.com/hub/Forensic-Entomology-corpse-analysis-with-flies-beetles