knab] THE MOSQUITOES OF SASKATCHEWAN 54I 



The town of Oxbow, about thirty miles north of the United States 

 boundary, was selected as a suitable location for study. It over- 

 looks the valley of the Souris River, and therefore, besides the 

 typical prairie country, also offers the diversified conditions of the 

 river valley. The prairie is rolling, and in the spring there are 

 numerous pools and small ponds. All but the largest ponds dry out 

 in the course of the spring and summer. It was in these prairie 

 pools of snow-water that mosquito larvae were found in greatest 

 abundance. On the river bottom-land no larvae were found, 

 although two species not found on the prairie occurred in the ravines 

 opening upon the river. 



.The first newly hatched mosquito larvae were found on May 6, 

 although as yet there had been but few mild days. In fact, on this 

 day there was a strong north wind blowing and icicles formed where 

 the water was dashed against reeds and branches. It was surpris- 

 ing, however, how rapidly the water, particularly in the ditches and 

 smaller pools, was warmed by the sun, so that it was very appre- 

 ciably warmer than the air. It was in these shallow pools that the 

 larvae developed most rapidly and in greatest numbers. The details 

 of larval development will be given under the separate species. 



In the following account the species are treated in the order of 

 their importance. Culiseta inornata Williston, which does not ap- 

 pear until later in the season, and which I did not have an oppor- 

 tunity to collect, is included. We owe specimens of this species to 

 the kindness of Dr. James Fletcher, the government entomologist 

 of Canada, and to Mr. T. N. Willing, of Regina. Eight species of 

 Aedes were collected. Four of these, Aedes spenceri Theo., A. 

 Uetcheri Coq., A. curriei Coq., and A. campestris D. & K., are pecu- 

 liar to the prairie regions. Two others, A. Htchii F. & Y. and A. 

 fuse us O. S., occur upon the prairie in lesser numbers. The two 

 species, A. canadensis Theo., and A. siibcantans Felt, were found 

 only in some deep ravines opening upon the Souris River, and do 

 not occur upon the prairie at all. They belong to the eastern wooded 

 region, and have found their way up along the wooded shores of the 

 river. It is significant that they were found only in two ravines, 

 the mouths of which lie close to the river's margin. 



AEDES SPENCERI Theobald 



This is the common mosquito of the prairies of Saskatchewan, 

 and apparently occupies the entire northerly portion of the prairie 

 region of North America. It is very bloodthirsty, and its excessive 

 abundance makes life upon the prairie a torture during the early 



