June, '17] HERMS: CALIFORNIA MOSQUITO SURVEY 369 



pheles mosquitoes to distribute malaria among the employees who 

 may work toward evening during the rush season, or larvse may occur 

 in an open spring which supplies drniking water for the nearby fruit- 

 picking camp, etc. The successful operation of malaria campaigns 

 calls for specially trained men. 



Far too little attention is paid to the irrigation ditches and methods 

 of irrigation in northern California. Until this matter receives proper 

 attention there will always be more or less malaria in our irrigated 

 districts. This is further evidence that details are overlooked and 

 that the irrigation and drainage engineer to whom such matters as 

 mosquito control are often referred is not meeting the requirements, 

 that he is interested in the successful operation of the work at hand 

 and is not responsible for the water as it may prove a menace to health. 

 This is' not ordinarily within the scope of his work. That there is 

 little or no malaria in the irrigated districts of southern California is 

 a mere coincident in the problem of conducting water from place to 

 place in the most economical manner. 



The recent introduction of rice culture in California brings with it 

 new problems. These were studied with some care during the progress 

 of the survey. Rice culture is evidently most successful in regions 

 which also favor mosquitoes. In most instances both mosquitoes and 

 malaria have preceded rice culture in a given locality, and the intro- 

 duction of rice has merely increased the number of mosquitoes and the 

 cases of malaria. In certain sections there is strong antipathy toward 

 the rice industry because of its effect on health and comfort, on the 

 other hand the rice grower displays a feeling of indignation because 

 the entire responsibility is placed on his shoulders, in spite of the 

 fact that both mosquitoes and malaria preceded the advent of his 

 industry. 



Out of our study of the rice situation there have come several im- 

 portant conclusions, namely that the rice grower is guilty of careless- 

 ness and does not practice sound agricultural methods. He is intent 

 on quick returns at a minimum expense. The irrigation systems are as 

 a rule carelessly constructed with the result that the roadsides are 

 bordered for miles and in some instances actually covered by water. 

 It is this careless and profligate use of water which is responsible for 

 the enormous increase of mosquitoes. It seems quite reasonable to 

 believe that more than 50 per cent of the trouble will be eliminated 

 concomitant with the practice of scientific methods in the culture of 

 rice. 



Furthermore, after the water is drained from the fields in the autumn 

 great numbers of pools remain along the contour checks and the road- 

 sides in which mosquitoes continue to breed for some time after the 



