218 Arinals Entomological Society of America [\^ol. X, 



species is dominant from early mid-summer on or during the 

 period when the salinity rises to the degree favorable to it. 



In the beginning of a study of this sort the student may be 

 confused by his findings, for he may discover the larvse of both 

 species in the same pool with salinity either high or low. He 

 will soon find, however, that larvae under these conditions are 

 all well grown or that the extremely small larvae are of the species 

 favored by the salinity. This mix-up of large larva? of the two 

 species is due when the salinity is extreme in either direction, 

 in the writers opinion, to larval distribution by high tides. 



SOME UNSOLVED PROBLEMS. 



Many problems of mosquito work which are important from 

 the standpoint of the practical work of control are yet without 

 solution. 



Ditching systems on the salt marsh are rapidly multiplying 

 and some machinery especially adapted to the work of cleaning 

 and repairing them should be devised. 



Until the late summer of 1915 and the seas.on of 191G the 

 fresh water swamp mosquito had formed, except in the vicinity 

 of great swamps, a minor portion of the problem of control. 

 The fact that since that time it has been the dominant form 

 over a large part of the protected area indicates clearly that a 

 further study of its life economy must be undertaken. 



Collections of mosquitoes on the wings have failed to reveal 

 the flight habits of Anopheles quadrimaculatus Say. It is 

 rarely taken in collections except very near its place of breeding. 



The oils used for larvicides need to be standardized and a 

 really practicable larvicide soluble or at least miscible with 

 water should be found. 



A practicable way to reduce the mosquito fauna, which 

 survives the faithful practice of the present methods, should be 

 discovered, for the failure of the mosquito fighting machine in 

 any particular way, during trying weather, all too promptly 

 increases the ever present minimum to a troublesome number. 



