ACTIVITY 23

As the Worm Turns

Teaching Objectives:

1. Students will observe mealworms (Tenebrio molitor) over a period of several weeks.
2. Students will record their observations of the size, number, and activity of the mealworms at the end of each week.
3. Students will create graphs that demonstrate the increase or decrease in the size, number, and activity of mealworms in weekly increments.
4. Students will observe the differences between the larval and adult stages of mealworms and draw diagrams representing these two stages.

Materials Needed:

• Mealworms, ordered from Biological Supply Houses or purchased at a pet store; order both larval and adult stages
  
• Glass container with a lid that allows for ventilation (e.g., wire screening)
  
• Oatmeal
  
• Apple slices
  
• Spoon
  
• Pencil and paper
  
• Graph paper or computer graphing capability
  
• Ruler
  
• Magnifying glass
  
• Specimen dish
  

Procedure:

Use the spoon to place 5-6 mealworms in the specimen dish. Measure and record the worms' length in a journal. Record the color of the worms and their rate of activity

Using one insect, locate the different parts of the mealworm's body: head, thorax, and abdomen. Point out other obvious body parts such as eyes, antenna, legs, or wings that can be seen with the naked eye or a magnifying glass. Have the students diagram the mealworm's body.

Place the larvae in the glass container with oatmeal and apple slices. On a weekly basis, repeat the observation process and record the findings. As a class or by groups, graph the findings by a method of choice. If done by groups, compare the ways the different groups graphically display the same findings.

If the larvae mature into pupae, note the time at which this begins.

Diagram one of the adult mealworms (beetles), labeling its body parts in the diagram. So that the insects will remain inactive during this process, place them in the refrigerator prior to attempting to diagram them.

Make the following observations about the mealworms:

• Measure and record the lengths of several of the adult insects. Compare the larvae and adults. Which group has more consistent measurements from one insect to another?

• Which group is more physically active under normal room conditions?

• Which body parts do the two insect stages have in common?

Supplemental Activities:

Have the students write a paragraph on the advantages the adult mealworm has over its larva.

Research the use of insects as food by humans. Bugs on the Menu has information on this topic and includes two recipes. Have students use a recipe from this, another Internet site, or another source to create a dish that incorporates meal worms. Give extra credit to any student willing to try the food (with permission, of course, from his/her parents)! You can find recipe information at: Bugfood 2.

Hold mealworm races. Draw a circle on a piece of paper or fabric to serve as the "race track." Try using different colors of paper and different textures to see if differences occur. Mark the mealworms with something non-toxic on their backs in order to keep up with which worm is which. (Washable markers would be a good choice.) Graph race times and indicate whether color or texture has an influence on them.

Research the topic "Insects As Food for Man." Use the Internet as well as printed materials.