KNAB] THE MOSQUITOES OF SASKATCHEWAN 545 



absent from most of the small pools, which dry out in a few weeks 

 and form the favorite habitat of the larvae of A. spenceri. Although 

 next in importance to A. spenceri, this species is very much less 

 numerous. The larvae develop more slowly, and most of them do 

 not reach maturity until after the larvae of A. spenceri have disap- 

 peared. They seemed to thrive best in the deeper reedy pools of a 

 more or less permanent character, where they feed near the bottom, 

 ascending for air from time to time. On May 25 the larvae were 

 still in the second and third stages, and it was not until May 28 that 

 a larva in the last stage was obtained. June 10 the first pupa was 

 found, and the larvae were at that time nearly all in the last stage. 

 June 13 pupae were numerous, and by June 18 the larvae had all dis- 

 appeared and only a very few pupae remained. On May 27 the 

 larvae, in the third stage, were found in ditches and in a permanent 

 swamp which were so strongly alkaline that there was a white de- 

 posit along the margins. In the alkaline ditches pupae and full- 

 grown larvae of A. spenceri and small larvae of A. curriei were asso- 

 ciated with the larvae of A. fletcJieri. The adults bite in the day- 

 time and also toward evening. 



AEDES FITCHII Felt and Young 



The larvae of this species were usually found associated with those 

 of A. fletcheri, although usually in still smaller numbers. They de- 

 velop at the same time with Hetcheri and their growth is equally 

 slow. 



On the evening of June 19 I was fortunate enough to observe the 

 swarming of this species in a shallow depression at the head of one 

 of the ravines near Oxbow. The ground sloped gently from the 

 prairie, which at that point was 15 or 20 feet above the bottom of 

 the depression. When the swarm of males was first noticed, at 

 8.30 p. m., it was loosely organized, and there were perhaps forty 

 individuals, which gyrated and circled about close to the ground. 

 Close by there were some thorn bushes, and between and around 

 these there were several swarms of Chironomidae, but no mosquitoes. 

 In a short time other swarms of mosquitoes began to form in the 

 open, along the bottom of the depression and on the western slope, 

 where they were protected from the wind. These various swarms 

 kept close to the ground and spread out in such a way that they 

 might be said to have been loosely connected, but still there were 

 foci where the mosquitoes were massed closer together. At no 

 time was the top of a swarm more than four feet above the ground, 

 while it spread out to at least twice that diameter. The size of the 

 swarms gradually increased until, at 9 o'clock, one swarm contained 



