Illinois Natural History Survey - University of Illinois

The Naturalist's Apprentice: What is a Pest

OBJECTIVE: to develop a definition for the word "pest"

SKILLS/PROCESSES: generalization, classification, application, value judgments

VOCABULARY: pest, pesticide


1. Divide a section of the chalkboard into three columns. Label the column to your left "Pests"; label the center column "Reasons"; leave the third column unlabeled at this time. Ask the class to name insects that are pests; list these in the column to the left. As each insect pest is named, ask why we consider it to be a pest. Probe for as many reasons as students can provide, and encourage them to be specific. Write these reasons in the center column.

2. Ask for the names of animals other than insects that are pests. Add these along with specific reasons to the columns on the chalkboard.

3. Ask for the names of plants that are pests and add these, along with justifications, to the lists on the chalkboard.

4. Review with the class the column of reasons and ask them to define general categories into which those reasons might be sorted. These categories will depend upon the list of reasons, but they will probably include the following four in one version or another:

a. Carry disease

b. Eat our food or damage the plants or animals we grow

c. Damage our possessions

d. Cause inconvenience


List these general categories in the third column on the chalkboard, and head the column "Characteristics of Pests."


5. Working together, assign each reason in the center column to one of the characteristics in the column on the right by drawing an arrow from left to right. The abbreviated example on the next page indicates the kinds of respon-
ses you can expect.

6. Ask students to name some insects that they do not consider to be pests and to explain why these are not pests. Ladybugs, dragonflies, butterflies, and honeybees are likely to be named. Repeat for animals other than insects and for plants. Be sure to ask students to explain why they do not consider these to be pests.

7. Ask each student to define a pest on a slip of paper. You may collect these or ask for volunteers to read their definitions. In either case, decide on a class < definition of a pest. Whatever the particulars of that definition, be sure students realize that organisms are pests only when they interfere with us in some manner. A mouse in the house is a pest, but mice in the meadows are not. A flour beetle in the pantry is a pest, but beetles outside may not be.

8. Which pests listed on the chalkboard are pests sometimes and not at other times? Under what circumstances are they pests?

9. Conclude the activity by discussing briefly the ethics of pest control and pesticides. When should pesticides be used? How much "damage" is acceptable before we 
resort to the use of poisons?


EVALUATION Give students five minutes to write an answer to this question: When is a pest not a pest? Request that their answers include reference to three organisms commonly considered to be pests.



Activity excerpted from Illinois Natural History Survey Special Publication 9--Legacy of a Pest (a curriculum detailing the environmental problems associated with an introduced organism, the gypsy moth). To obtain a copy of this publication, contact the Illinois Natural History Survey Distribution Office at 217-333-6880.


Biodiversity, Wetlands, and Biological Control: Information and Activities for Young Scientists--Purple Loosestrife: A Case Study is a new curriculum developed to provide middle school students with an appreciation of the complexity of natural wetlands, the threats from exotic invaders, and the potential of biological control as a management tool. This curriculum is currently only available through a workshop. Please contact Dave Voegtlin at 217-244-2152 for more information.

Susan Post, Center for Economic Entomology, and Carolyn Nixon, INHS Office of the Chief

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