160 ELEMENTARY LESSONS ON INSECTS 



Three lessons follow that are of a strictly economic 

 character. Each may be divided or expanded or repeated 

 with new materials if desired. They are: 



14. Insect injuries and their control. 



15. Wormy apples. 



16. The seasonal history of a plant pest. 



LESSON 14 



Insect Injuries and Their Control 

 I. Crop Pests 



Select some common crop such as apple or potato. Go 

 out where it grows and find as many as you can of the kinds 

 of injuries to it outlined in pages 157-59. 



During the growing season both biting and sucking insects 

 will be readily found in almost any garden. Leaves wholly 

 or partly consumed will mark the work of the insects with 

 biting jaws; leaves badly curled or wrinkled, the work of 

 the sucking insects. Select insects of both sorts for experi- 

 ment. Food plants with their depredators on them may be 

 kept fresh for a few days under bell-jars in the laboratory, 

 if the work cannot be done in the garden. 



Experiments with Insecticides 



Food poison experiment. — For the biting insects, dissolve a 

 teaspoonful of arsenate of lead in a quart of water and spray 

 it on the leaves to be eaten by the insects. 



