HABITAT 



169 



In the laboratory S.fasciata may be kept alive for some time 

 at 7-8 C., if kept in a refrigerator and thereby protected 

 from currents of air. When exposed to a similar temperature 

 in the open air it soon dies. At o C. the insect succumbs in 

 a few seconds and, on the other hand, a temperature of 37 C. 

 is also rapidly fatal. 



This susceptibility to variations in temperature causes this 

 mosquito to be confined to certain degrees of latitude, from 

 40 N. to 40 S., or more exactly between the two isothermal 

 lines of 20 C. Owing to the ease with which it may be carried 

 from one country to another by means of ships, the species is 

 now found in most of the regions between these limits. The 

 accompanying map (Fig. 48) represents the distribution of 



Fig. 48. The distribution of Stegomyia fasciata. 



5. fasciata, and it will be noticed that the insect especially 

 occurs along the coast lines and the banks of large rivers, 

 where the requisite conditions of humidity are fulfilled. It is 

 absent from those regions in which the temperature during 

 the night falls so low as to be harmful to reproduction. 



