MOSQUITOS OR CULICIDAE OP NEW YORK STATE 249 



effort, even in the case of these two species, will afford consid- 

 erable relief, which is certainly true of others liable to become 

 at all troublesome. A number of instances have been placed 

 on record in recent years, proving the efficacy of operations 

 confined to small areas, and further investigations may show 

 that the migrations observed by Dr Smith were somewhat local 

 and brought about by peculiar conditions. Mr G. 0. Davis has 

 recently published data showing that mosquitos in arid portions 

 of California are carried over 20 miles by steady, gentle breezes. 

 Eailroad trains have been suggested as an efficient means of dis- 

 seminating mosquitos, but Dr Smith's observations, showing that 

 while a train might become filled with mosquitos while passing 

 through an infested marsh, it was practically free when the 

 haunts of the mosquitos were left behind, would seem to indicate 

 that this method of transportation is of relatively small import- 

 ance. Eailroad trains might, however, convey small numbers to 

 favorable breeding places, where the insects would be able to sur- 

 vive for a few generations, and in this way centers might become 

 established. Ships are probably very efficient in conveying species 

 from one country to another, since Kowe has observed 12 foreign 

 species on a ship in quarantine at New York. 



Life history. Only a few years ago it was supposed that the life 

 histories of most species of mosquitos were substantially identical. 

 The great impetus given to the study of this group by the recent 

 demonstration that certain forms were capable of conveying 

 malaria and yellow fever, has practically disproved this notion, 

 and now we know that there is considerable variation in their life 

 histories and habits, as will be seen by reference to accounts of 

 different species on the following pages. 



Hibernation. At one time it was presumed that the winter was 

 passed solely by the adults, and while this is undoubtedly true of 

 certain species, others hibernate in the egg stage and still others 

 as larvae and possibly pupae. Several observers have noted the re- 

 sistance of larvae of this insect to cold and have placed on record 

 instances where they have been frozen repeatedly and survived. 



