Insecutor Inscitiac Mcnstruus 



Vol. V. JULY-SEPTEMBER, 1917 Nos, 7-9 



THE MOSQUITOES OF THE PACIFIC NORTHWEST 



(Diptera, Culicidce) 

 By HARRISON G. DYAR 



In studying the mosquitoes of the Sierra Nevada Mountains 

 of CaHfornia in 1916, I was confronted by the problem of a 

 certain similarity between Aedes tahoensis of the Sierras and 

 A. pullatus of the Rocky Mountain region of British Columbia 

 and Idaho. The two differ in the nu§iber of larval head hairs, 

 and it was thought that tahoensis might extend up the Cascades 

 through the Pacific Northwest to British Columbia, where the 

 mountains meet, and so, the two species converge. Accord- 

 ingly a short exploration was undertaken of the mountains in 

 Washington State in the spring of 1917. Specifically, Glacier, 

 in the Mount Baker region ; Longmire Springs, in the Mount 

 Rainier region, and Lake Cushman, in the Olympics, were 

 visited. 



Concerning the special problem in hand, it was determined 

 that tahoensis does not follow up the Cascades, but is replaced 

 by an allied species, and therefore the geographical isolation 

 of tahoensis and pullatus is assured, together with their dis- 

 tinctness. This is quite clearly indicated by the very different 

 climatic and floral conditions obtaining in the Sierras, as a 

 short stay will readily convince one. In the Northwest it 

 rains, producing a dense forest with moss and undergrowth ; 

 in California there is no rain, the forest being open and dry, 

 while the lowland is treeless. 



As compared with California, the Pacific Northwest is poor 

 in mosquitoes, both in individuals and in the number of species 

 concerned. But three black-legged species of Acdcs were found 



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