October, '21] herms: axopheline notes 411 



convenient to consolidate all the counties north of Tehachapi into two 

 divisions, nameh' Northern California and Middle California, designating 

 everything south of Tehachapi as Southern California. 



Although this paper is not concerned with the occurrence and distri- 

 bution of malaria in California it is nevertheless interesting and apropo as 

 well to re\dew the conclusions reached in the malaria-mosquito survey 

 recently completed (See U. S. Public Health Reports Vol. 34, No. 29)viz :-^ 



Comparing the average annual death rate per 100,000 of Northern 

 California and Middle California it will be seen that the rate is almost 

 the same, namely 4.9 for the former and 4.7 for the latter. Furthermore, 

 the percentage of Anophelines taken in both divisions is not widely 

 divergent, i.e., 38 per cent in the former and 31.1 per cent in the latter 

 and of these A. occidentalis and A. punctipennis combined represented 

 77.9 per cent of the total Anophelines in the northern division and 56.9 

 per cent in the middle division, the remaining being A. pseudopuncti- 

 pennis, believed to be negligible in its relation to m-alaria. This stands in 

 rather striking contrast to the conditions in Southern California, where 

 the average annual m,alaria death rate is only .9 per 100,000 population, 

 and where 49.6 per cent of the mosquitoes collected were anopheline,of 

 which however 69.3 per cent were A. pseudopuncHpenms. It will, 

 furtherm.ore, be seen that the average num.ber of m,osquitoes per col- 

 lection for these two divisions (northern and m.iddle) was 9.9 for North- 

 em California and 13.1 for Middle California, indicating a greater abun- 

 dance of m.osquitoes for the latter, but it is interesting to note that the 

 relative num.ber of A. occidentalis and A. piinctipennis^jzombmed per 

 collection was ven^ similar, nam.ely 3.6 for the northern area and 4.1 for 

 the middle area, corresponding m.ore or less closely in proportion to the 

 m.alaria death rate, and that the average num.ber of mosquitoes per 

 collection for Southern California was 10.1, while the average number 

 per collection of A. occidentailis and A. punctipennis combined was only 

 1.7 and the malaria death rate .9 per 100,000. 



Although the San Joaquin Valley is com.m.only regarded as not greatly 

 unlike the Sacram.ento \^alley topographically, it will be seen that the 

 annual m.alaria death rate for the latter is alm.ost twice as high as the 

 former, nam.ely 6.3 per 100.000 for the San Joaquin and 10.9 for the 

 Sacram.ento. It would appear that this high rate for the latter is ex- 

 plained by the high rate of effective Anopheline carriers, i.e. 46.0 per 

 cent of all mosquitoes taken in the Sacram.ento Valley were A. occi- 

 dentalis and A. punctipennis com.bined, and only IS.S per cent consisted 

 of these two species in the San Joaquin Valley. 



