Video of Pig Carcass Decomposition

Entomology 109

Forensic lab

4/21/04

Video of pig carcass decomposition

1. What insects predominate in the carcass?

2. How long a time period does the tape cover?

3. Do carrion flies pupariate in the carcass? How could this kind of information influence a forensic entomologist?

Carrion Insects

What orders do you see represented in the collection of carrion insects? Which orders do you see represented the most?

Road kill

Look at the dead animal on display.

1. What kind of animal is this?

2. Using the reference collection try to identify to order (and species wherever possible) of the insects infesting this carcass:

a.

b.

c.

d.

e.

3. You will be given a series of larvae of Calliphora vomitoria, the blue bottle fly, found on/in the road kill featured in lab. Measure the length of the larvae provided and compare these lengths with those reported in the table below. Estimate the age of each of the larvae based on the data in the table and the temperature information given in class.

1.

2.

3.

4.

How would you use this information as a forensic entomologist?

What factors might influence the relationship between age and size of maggots?

Table 2. The development of body length (in millimeters) of some fly species during their metamorphosis at 72° F (L = Larva, P = Pupa, A = Adult fly).

4. Light response in carrion flies

Many environmental factors affect the distribution and abundance of insects in carrion. Light and humidity are two such factors. In this experiment you will determine the phototactic responses of Sarcophaga bullata.

Drape a long glass tube with black fabric so that half of it is exposed to light and half is completely dark; cover up one end so that light enters in only one end of the tube. Place a number of adult flies (anesthetized with carbon dioxide) in one end of the tube. After three minutes, remove the black fabric.

At what end of the tube are the flies located?

Calliphora, the bluebottle fly, prefers shade and Lucilia the greenbottle fly prefers sunshine; how does Sarcophaga bullata compare to these close relatives?

Now place several maggots of S. bullata in the glass tube and repeat the experiment.

Are the results different?

How might you use this sort of biological information if you were a forensic entomologist?

5. Odor vs visual cues in carrion-finding

Two hunks of ground beef will be provided to female S. bullata in a cage. One hunk of beef is covered tightly with plastic wrap, and one piece is wrapped loosely with cheesecloth.

Watch the behavior of the female flies as the beef is placed in the cage.

Which of the two hunks of beef do you think provides more in the way of visual cues as to its identity? Which hunk provides more in the way of olfactory cues as to its identity?

Count the number of female flies landing on each hunk of beef in a ten-minute interval. On which piece of beef do more flies land?

What can you conclude from this experiment about the orientation behavior of this species of flesh fly?