Páginas: 20 (4906 palavras) Publicado: 20 de abril de 2012
“The horses in the pasture fidgeted with anticipation when
they heard Mr. Johnson’s lawn mower nearby. Little did
anyone know that soon one of them would end up dead as a

By Lisa Carloye, Washington State University
Stephen Bambara, NC State University
(Adapted by S. Bambara from “Of Maggots and Murder” by L. Carloye)

This is a hands-on lesson in which 4-H’ers evaluateevidence from four animal death
scenarios. For each scenario, they are given a sample of simulated maggots that
were collected from a fictional corpse and are asked to figure out the postmortem
interval in which the insects developed and determine whether foul play was
involved in the death. This exercise is adapted from a lesson used by college biology

Life Skills:
Critical thinking,problem solving, teamwork, communicating, learning to learn.
1. To appreciate the practical application of entomology in society.
2. To learn the concept of “succession” of insect life in the role of decomposition.
Four lessons requiring approximately 20 minutes each.
Also included at the end is an optional, related activity involving monitoring insect
succession in adecaying chicken gizzard over several weeks. Review the activity to see if
it can be useful or applicable to your program.

Flies around the corpse of a cardinal.


Crime Solving Insects

Materials You’ll Need:
• Life history of flies sheet (provided, Table 1, page 13, one for each team)
• Ecological information sheet (Table 2, page14, one for each team)
• Police report informationsheets for Cases 1-4 (provided, one set for each team,
pages 9-12)
• Rulers measuring millimeters (one for each team)
• Colored pipe cleaners—white, blue, yellow, pink, and brown
• Plastic sandwich bags filled with appropriately measured lengths of colored pipe
cleaners (1 for each case, 4 for each team)
• Scissors (one) to cut pipe cleaners
• Forceps or tweezers for each team (optional)
•Plastic or latex gloves (optional)
Before the Meeting:
Prepare a Crime Report Pack for each team of 4-H’ers.
The Crime Report Pack contains:
• Maggot bag of cut pipe cleaners (4, one for each case using Table 3, page15).
(Label each bag with a case number.)
• Police report information sheets (one for each case)
• Life history sheet (Table 1, page13)
• Ecological information sheet (Table 2,page14)
• Ruler measuring millimeters
• Four Common Flies Used in Forensic Investigation (photos, provided, one for
each team of 2 or 3 4-H’ers, page 8) (optional)
• Forceps and gloves (optional)
The ordered development of flies on a dead animal is predictable. Because of that, the
flies can be used to help determine the time of death or other factors that may have legalimplications. This interactive learning activity was originally developed for use in a
college general biology class to illustrate principles of community ecology and ecological
succession, the idea of an ecological niche, and the role of life history, and to illustrate
how basic biology can have an unexpected practical use.
This activity is of minimal cost and may be conducted without the need of astrong
biological background, either in a classroom or at tables. Each of the four death scenarios
features a slightly different twist and takes about 20 minutes to complete. Each case can
stand alone, or all can be worked through sequentially, as time permits.


Crime Solving Insects

Lead In:
When an animal dies, flies are among
the first to find and colonize the carcass,
usuallyarriving within 10 minutes of
death. As the carcass decays, the
environmental conditions within it
change. It becomes drier, the
temperature rises, and tissues break
down. In fact, the process of decay is
one of ecological succession whereby a
series of predictable changes occur, in
succession, as the carcass progresses
from the “fresh” stage, where the body is
intact and decay has...
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