QUESTIONS AND REFERENCES 367 



are increased by certain animals that destroy others that feed upon 

 or otherwise destroy man's commodities. We have learned also 

 some of the ways in which these destructive animals work. We 

 see the toll taken by destructive animals, insects in particular, so 

 great that one tenth of the fruit of man's labors is wasted. But 

 we learn also that this destruction is all a part of the life which 

 animals lead in order to exist. They are the destructive force on 

 the earth, using the products built up by the green plants. 



Problem Questions 



1. What is plankton and of what use? 



2. What lower animals are directly of use as food? 



3. Why are lobsters and other shellfish being exterminated? 



4. How do fish compare in economic importance with other animals which 

 are used as food? 



5. State the uses of birds. List different birds according to the good they 

 do. 



6. List all the animal products used as food and as clothing. Other uses? 



7. List animals destructive to food and show how each does harm. 



8. In what indirect way has the cotton-boll weevil done good ? 



9. What useful insects can you name, and why are they useful? 



10. What are the agencies which help to control the harm done by anima's? 

 Show how these agencies work. 



11. Why is the rat marked for extermination? Can you list any other 

 animal pests to go with the rat ? 



Problem and Project References 



Hunter, Laboratory Problems in Civic Biology. American Book Company. 



Folsom, Entomology. P. Blakiston's Son and Company. 



Herrick, Household Insects and Methods of Control. Cornell Reading Course. 



Hornaday, Our Vanishing Wild Life. New York Zoological Society. 



Hodge, Nature Study and Life. Ginn and Company. 



Reese, Economic Zoology. P. Blakiston's Son and Company. 



Stone and Cram, American Animals. Doubleday, Page and Company. 



Toothaker, Commercial Raw Materials. Ginn and Company. 



Hornaday, The American Natural History. The Macmillan Company. 



Jordan and Evermann, American Food and Game Fishes. Doubleday, Page 



and Company. 

 Shaler, Domesticated Animals. Charles Scribner's Sons. 

 Farmers' Bulletins, 513, 630, 740, 801, 1294, 1326, 1346, 1353, 1371. 



