404 SCIENCE OF HOME AND COMMUNITY 



and there has been a constant decrease each year 

 since. 



Previous to the digging of the Panama Canal, Colonel 

 Gorgas was appointed sanitary officer of the canal zone. 

 He employed similar methods against the mosquito there, 

 with the result that yellow fever has apparently been elimi- 

 nated and malaria greatly reduced. This work had a very 

 important bearing on the building of the canal, which would 

 undoubtedly have been seriously interfered with if this work 

 of Colonel Gorgas in doing away with the mosquito had not 

 first been done. 



In San Antonio, Texas, the work of finding and destroying 

 the breeding places of mosquitoes was taken up by the school 

 children, and as a result the mortality from malaria was 

 reduced seventy-five per cent the first year, and entirely 

 eliminated the second year. 



In the town of Crosset, Arkansas, with a population of two 

 thousand, 60 per cent of the time of the doctors was taken 

 up in treating malaria. During the year 1917 a campaign 

 against the mosquito was carried on costing $2500, or $1.25 

 per person. As a result the number of cases of malaria was 

 reduced 82 per cent. 



LABORATORY EXERCISE 34 



Purpose. To study the life history of the mosquito and to 

 find methods of destroying it. 



Materials. Mosquito wigglers in tumblers of water covered 

 with mosquito netting, fish, tadpoles, water insects, kerosene. 



Directions. I. Study the larva and note (a) its method of 

 breathing, (b) its method of moving, (c) position when at rest. 

 What is the longest time that a larva stays away from the sur- 

 face? 



2. Compare the pupa with the larva in the three points 

 given above. 



3. When the adult emerges, notice its resting position. 

 Describe the mouth parts. 



