PROBLEM 123 



149 



ment of Agriculture (see list of Reference Books) and Civic Biology, 

 pages 209-211. 



Method and Observations. — Fill out the preceding table 

 on the food of some birds, using references suggested above. 



Conclusion. — Which of the birds are of use to man ? Of harm ? 

 Which may be of both harm and use? Explain your answers. 



Problem 122: What are the causes of decrease in the 

 number of birds ? 



Method and Observations. 

 — Using your own experience 

 and the information obtained 

 from Hornaday's Our Van- 

 ishing Wild Life, complete a 

 table like the accompanying. 



Conclusion. — In a care- 

 fully written paragraph sug- 

 gest some methods of prevent- 

 ing the decrease of our helpful 

 birds. 



Problem 123 : To study the life history of the mosquito. 



NOTE. — There are four distinct stages in the development of the mosquito : 

 egg, larva, pupa, and adult. These will be taken up and studied in order. 



a. The Egg 



Method. — The eggs of mosquitoes are laid on the surface of still 

 salt or fresh water pools from April to October. By placing a 



can of water in a lot, we can 

 often obtain the small rafts 

 of eggs of the common mos- 

 quito, the culex, and less often 

 the single floating eggs of the 

 malarial mosquito, the anopheles. Any standing water, especially in 

 barrels, old cans, neglected drains, catch basins, and swamps, may 

 make a near-by neighborhood almost uninhabitable. The yellow- 

 fever mosquito, stegomyia, is not found in the North but is found 

 in the warmer parts of the United States. 



