KNAB] THE MOSQUITOES OF SASKATCHEWAN 543 



ping back again, but without unison. When disturbed by the wind 

 their flight became more rapid, and sudden gusts caused them to 

 fly to the ground. Several pairs were seen flying off in copula, and 

 once the female was observed approaching the swarm from beneath. 

 There was a second swarm of males farther down the ravine, about 

 half way up the slope, and, like the other, at the margin of the shrub- 

 bery filling the bottom of the ravine. In this case a swarm of very 

 small Chironomids was mixed with the lower part of the swarm. 

 In crossing an open field in the river valley at 6.30 p. m. a swarm 

 of males formed over my head and, following me, increased to the 

 number of perhaps two hundred. They disappeared when I ap- 

 proached the woods on the edge of a ravine. This experience was 

 repeated in the field beyond, and upon nearing the edge of the woods 

 the swarm again departed and could be seen in the middle of the 

 field. Several days of cold and cloudy weather followed, during 

 which the mosquitoes remained quiescent. After the heavy rain of 

 the previous night, the afternoon of June 9 was warm and sunny 

 and the mosquitoes exceedingly abundant and active. At 6.30 p. m. 

 I walked toward the river with a companion. As soon as we had 

 left the town the female mosquitoes began to rise out of the grass 

 and alight upon us. There was a brisk breeze blowing and the mos- 

 quitoes settled on the leeward side of our bodies, and a cloud of 

 them followed us, keeping for the most part about our legs. These 

 clouds increased rapidly and became very aggressive as we passed 

 down into the valley, wdiere we came upon a cloud of males on the 

 open prairie. When we approached them they formed in two 

 swarms over our heads. My companion, being the bulkier man, 

 attracted a much larger swarm. We thus each had two swarms 

 of mosquitoes about us ; the one. of females, kept about the lower 

 part of our bodies, while the other one, of males, kept above our 

 heads. Several copulations were noted. Upon entering a ravine 

 the males all left us and only a part of the females followed. Upon 

 emerging on the other side of the ravine a new swarm of females 

 quickly gathered, and shortly we came upon another large swarm of 

 males, which again concentrated above our heads in separate 

 swarms. It was now 7 o'clock, but still bright daylight at this 

 season of the year. The swarms of males I judged to contain many 

 hundreds, if not a thousand, individuals. These swarms, in close 

 formation, followed us up the long hill and continued with us nearly 

 to the town, in the end being much disturbed by the wind. About 

 7 o'clock quite a number of copulations were observed. The females 

 approached the swarm from beneath and left it united with a male, 



