70 Journal New York Entomological Society. [Vol. xiv. 



reached the conclusion that the American form known as Culex fati- 

 gans represents a distinct species peculiar to the tropical and subtrop- 

 ical regions of this hemisphere. 



The author believes that Stegomyia fasciata and Culex fatigans are 

 inseparable allies, always to be found together, the nocturnal Culex 

 fatigans supplementing the diurnal Stegomyia fasciata in the persecution 

 of man and the two constituting a strong combination against him. 

 He believes that future studies will show that the influence of these 

 two mosquitoes, over and above the grave diseases which they trans- 

 mit, is the principal cause of tropical anemia. 



Attention is called to the occurrence of dwarf specimens, both of 

 Stegomyia fasciata and of Culex fatigans, a circumstance of considerable 

 importance as they succeed in passing through screens effectual against 

 normal mosquitoes. At certain seasons these dwarfs are more numer- 

 ous and even become the predominating form. Thus it appeared that 

 in the last weeks of October and in November, just before the opening 

 of the rainy season, these small females were particularly numerous. 

 These dwarf mosquitoes are the product of adverse conditions during 

 development, such as the reduction of water and food in the dry sea- 

 son, so that there may be said to be a small sestival generation. It is 

 a wrong opinion that the individuals of this dwarf race are less agres- 

 sive and blood-thirsty than those of normal size ; they behave in every 

 way the same and their bite is equally painful. 



One cannot suppose that on the whole Brazilian coast, southward to 

 Rio Janeiro or Santos, there is a single place where the development 

 of Stegomyia ever comes to a standstill. There are larvae throughout 

 the year, although there will be fluctuations in the rate of development 

 corresponding to hot or cold, wet or dry season in the different locali- 

 ties. Inquiries into these conditions gain particular importance 

 through their relation to the periodicity of yellow fever. 



From the experiments it appears that Stegomyia fasciata shows a 

 decided preference for human blood over that of the guinea pig, and 

 human blood seems to have a more favorable effect upon oviposition. 

 Reptilian blood, that of a lizard ( Tropidurus torquatus) was offered 

 but not accepted. 



As all other mosquitoes are extremely sensitive to currents of air it 

 is remarkable that Stegomyia is quite indifferent to even a strong wind. 

 The author found that a strong wind blowing into a window, or the 

 current of air from an electric fan, did not in the least interfere with 



