356 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



with the latter. No experimental work has been done to show that 

 A. ocddentalis is susceptible to the parasite of malaria but since it is 

 one of only two anophelines that are found in highly malarial districts 

 and the other, — A. pseudopunctipennis, is only slightly susceptible, it 

 seems reasonable to believe that it is the chief carrier. To this cir- 

 cumstantial evidence might be added the additional reminder of its 

 close connection and perhaps synonomy with A. quadrimaculatus, a 

 proven carrier of malaria in many parts of the United States. 



Beyer and his associates stated that A. quadrimaculatus could be 

 infected with the tertian and quartan types of malaria but not with 

 estivo-autumnal. However, Hirshberg succeeded in infecting eight 

 out of 48 specimens of A . quadrimaculatus that were allowed to feed on 

 a volunteer suffering with the estivo-autumnal fever. Von Ezdorf , in 

 a later paper, states conclusively that A. quadrimaculatus is sus- 

 ceptible to all three types of malaria. 



A. pseudopunctipennis has always been looked upon doubtfully as a 

 malaria carrier. Darling succeeded in infecting four out of 27 of this 

 species with estivo-autumnal parasites, but a very small series of ex- 

 periments with the parasites of the tertian and the quartan types of 

 fever proved negative. 



The apparent contradictions of the different findings regarding the 

 infectivity of the same species of mosquito, is by no means limited to 

 those above stated. The same type of contradictions is prevalent 

 throughout the literature of infectivity experiments. This may be 

 due in some cases to faulty technique, confused nomenclature, or the 

 failure to state what type of malaria parasites were used for the experi- 

 ment, for different types of malaria are carried by different species of 

 Anopheles. Many times mosquitoes have been listed as non-malaria 

 carriers on the basis of experiments with one type of malaria although 

 they were the most important carrier of another type. Mitzmain has 

 proved this in showing that A . punctipennis is a strong carrier of tertian 

 fever but absolutely negative to estivo-autumnal. Another source of 

 error seems to be in the failure to consider ecological factors. Some 

 species seem capable of carrying malaria in one district while repeated 

 attempts to infect them in other portions of the country with the same 

 type of malaria invariably result negatively. Majoribanks states 

 that A. listoni is the chief carrier in parts of Bengal and although oc- 

 curring in large numbers in western India has never been found in- 

 fected despite the fact that malaria is endemic there. 



Considering both the circumstantial and experimental aspects of 

 the California problem, I feel that we can safely say that in the rice 

 districts A. ocddentalis is the important carrier with perhaps a few 

 scattered infections due to the agency of A. pseudopunctipennis. 



