MALES OF MEGARHINUS 131 



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, the 

 pair drifting away toward the ground and the union lasting but a short time. 

 They copulate face to face, grasping each other with their long legs, the female 

 in the upper position, the male back downward. This day proved the maximum 

 of activity for this species of mosquito. No more swarming of males or matings 

 were observed." 



In the same paper occurs an account of the swarming of Aedes fitchii, also 

 in Saskatchewan. Following is the description: 



" 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 brushes, and between and round these were several swarms of 

 Chironomidse, 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 con- 

 tained several hundred males. Copulation took place most frequently between 

 9 and 9.15, but matings were observed both earlier and later. The females en- 

 tered the swarm from beneath, when they were seized by one or more males. 

 Union takes place ' face to face,' the pair flying obliquely upward for several 

 yards. Then the pair would either separate promptly or swing out end to end 

 and struggle to disengage themselves. In this latter case both of them could be 

 seen to jerk violently and rapidly in their efforts to free themselves, and the 

 pair would slowly rise, but make no appreciable progress in either direction. 

 When two males seized a female the group would rise straight into the air, 

 apparently engaged in a violent struggle, one of the males finally uniting with 

 the female or all of them separating. In one case four individuals rose thus, 

 scrambling over each other, so to speak. The swarm was watched until 9.30, 

 when the twilight was already quite deep ; copulation appeared to have ceased 

 and the swarms were gradually breaking up." 



Surgeon E. H, Ross remarks as follows regarding the mating-habits of 

 Aedcs [Acarto7nyia] zammittii of the Mediterranean region. " Coitus does not 

 necessarily take place on the wing, for I have observed it occur when the female 

 is resting on the edge of the glass jar or sitting on the rock; the male clasping 

 the female when she is sitting." 



Knab has observed that the males of Megarhmus tend to congregate upon a 

 certain bush, alighting upon prominent leaves. linear Puntarenas in Costa Rica 

 he captured six males of Megarhinus moctezuma upon a single bush. When 

 approached they would fly up but alight upon another leaf of the same bush; 

 two that were frightened away returned to the bush after a short time. No 

 others could be found anywhere in the vicinity. Mr. J. K. Thibault, Jr., of 

 10 



