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Forensic Entomology Mini-Lesson

Driving Question: How do insects infested on a deceased body help to determine the time and location of death?

In this lesson you will learn about how a body, left in the exposed elements can lead to clues about time and location of death.  When you think of insects on a body, you call to mind Blow Flies and Beetles.  However, there are other insects used to determine the time and location of death.

Engage

The article below describes types of insects beyond Blow Flies and Beetles in the study of Forensic Entomology.  Click the title button next to the picture of the noctuid caterpillar.

Explore

A body has been discovered!  Use the online interactive to determine the time of death.  Recall from last lesson, the tools Forensic Scientists use to collect evidence of the crime as well as determine the time of death.  The interactive below allows for the use of insects to determine the time of death.

Explain

A Forensic Entomologist will use their knowledge of insects that will help to determine the time and location of death. This information can be helpful in criminal investigations when a death is under investigation. Forensic entomologists have several job functions. These job functions are as follows:

  1. They can identify insects and the stage they are in during their life cycle. This will tell you how long the insect has been on the body.

  2. Forensic Entomologists will collect and identify insect samples for evidence in a future criminal prosecution.

  3. The Forensic Entomologist will use insect life cycle and weather conditions to determine the time of death versus the time of discovery.

  4. Sometimes Forensic Entomologists will be used as expert witnesses in criminal cases.

Test the insects collected for presence of drugs, poisons or alcohol. Since these insects are feed on the corpse, the chemicals in the corpse will be found in the insects.

Most of the time, the insects that are used in criminal investigation are flies and beetles. Flies tend be the first species of insect to infest a fresh corpse. This occurs at any time during the first three months of death. Beetles will begin to arrive and infest the corpse between three and six months. Some beetles will infest the corpse years after death.

Enhance/ Extend

Weather

Investigators will take weather factors such as precipitation and temperature when determining the time of death. Temperature can be a measure of the air, ground or surface where the body is found. Factors that affect estimates of time of death include how the body was disposed (wrapped or not wrapped in a material that would prevent invasion of insects), presence of predator insect species, or posions or drugs in the body that would kill insect development.

 

Blow Fly Life Cycle

Click the image below to access the article of the life cycle of a blow fly. Make sure to click next to view the entire article. There are 7 detailed images.

Enhance: When investigating the death, insects are often the first to arrive on the scene.  Insect evidence is used to determine the time of death as well as if the body died in its current location or if it was moved after death.  Insects can also identify the location of wounds, mortal and defense.  Insects can also evaluate the types of medications that were ingested prior to death.  You are to complete the following activity to assist the forensic entomologist determine the elapsed time since death.

 

Extend: Once you have completed the activity, you are to write a 3 paragraph essay.  The first paragraph should include an explanation for completing this activity as it realates to our driving question: "How do insects infested on a deceased body help to determine the time and location of death?"  The second paragraph should include a description of the process used to complete the activity.  Finally, the third paragraph should include your results, data and conclusions drawn from this activity.  Your essay will be submitted to your language arts teacher for a summative essay grade as well as to your forensic science teacher for a lab grade.  Make sure to use the standard writing rubric provided by your language arts teacher for proper credit within the language arts submission.

Evaluate

For this activity, you are to determine the time of death based on the presence of insects. You have  a choice of two activities.  You will work with your lab group to complete this activity.  

 

Choice 1:  You are to complete the simulated 4H Crime Solving Insects activities 1-4 using knowledge provided in this lesson, independent research (document sources in your lab writeup) as well as infomation provided in your lab.  You are to complete a full writeup using one of the following online collaboration tools: Google Docs, PBWorks, Flowboard or Open Class.  You may use the format found within the 4H activity guide.  (Student guide with teacher annotations are provided by clicking the link below).

4H Activity

 

Choice 2:  You may complete a hands on activity using commonly found materials around your home. Each team member should collect data independently to identify similarities within the same area.  Your team should use one of the following collaboration tools to design your activity: Google Docs, PBWorks, Flowboard or Open Class.  Your activity must include the use of a raw chicken leg as the "body" and the "body" must be placed outside away from wild "critters" that may find your chicken leg tasty.  The remainder of the activity can be designed by you.  Your goal is to design your experiment to determine the time of "death" (when you placed the chicken outside) by the presence, type, and quantity of insects.  

Lesson Resources: 

AKS Standards- Forensic Science: 

A - Characteristics of Science  

  • apply computation and estimation skills necessary for analyzing data and following scientific investigations 

  • communicate scientific ideas and activities clearly 

  • demonstrate knowledge of scientific processes and inquiry methods

  • use the concepts of system, model, change, and scale when exploring scientific and technological matters

  • use tools and instruments for observing, measuring, and manipulating objects in scientific activities

 

B - Academic Knowledge and Skills 

  • apply knowledge of evidence to crime scene analysis

  • describe the role of the forensic investigator at the crime scene and in the collection of evidence 

  • describe the use of computer databases in forensic investigations

  • investigate the role of entomology in determining time of death

 

ISTE Standards:

1. Creativity and Innovation

1C: Use models and simulations to explore complex systems and issues.

1D: Identify trends and forecast possibilities.

 

2. Communication and Collaboration

2A: Interact, collaborate and publish with peers, experts or others employing a variety of digital environments and media.

2D: Contribute to project teams to produce original works or solve problems.

 

3. Research and Information Fluency

3A: Plan strategies to guide inquiry.

3B: Locate, organize, analyze, evaluate, synthesize, and ethically use information from a variety of sources and media.

3D: Process data and report results.

 

4. Critical Thinking, Problem Solving and Decision Making

4C: Collect and analyze data to identify solutions and/ or make informed decisions.

Instructor: Forensic Science Teacher, Biology Teacher, Zoology Teacher, Entomology Teacher, Environmental Science Teacher

Grade Level:  This is an 11th or 12th grade 4th year science course.

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