128 MOSQUITOES OF NORTH AISIERICA 



death in the killing-bottle. It could not be determined if in the slow flight of 

 the united pair the female leads off as is the case with pipiens, but it is to be 

 presumed so, as she is the larger. Neither could it be positivel}'^ ascertained 

 whether any females formed part of the swarm. None were seen to enter at the 

 time copulation took place, but with the rapid and confused movements of the 

 members of the swarm (some flying out of the swarm and back again, as de- 

 scribed above) it was impossible to keep all the individuals under close observa- 

 tion. However it is safe to conclude that, as in pipiens, the swarm proper con- 

 sists wholly of males — certainly the fifteen specimens captured out of the swarm 

 on Oct. 7 were all males. If there is any choice made in the selection of a mate 

 it must be on the part of the female, for there appears to be no effort made, or 

 any struggle, on the part of the males to secure the female entering the swarm. 



" An interesting fact was the prompt reaction of the entire swarm to sound. 

 The sound of the voice in conversation would, at the first shock, precipitate the 

 entire swarm about a foot, and the mosquitoes would continue in rapid and con- 

 fused movement while the speaking continued. This effect could be noticed even 

 when one spoke in quite a low voice, and a pistol-shot, perhaps half a mile off, 

 precipitated the swarm in the same manner. When silence was restored the 

 swarm immediately resumed its normal flight. The experiment was repeated 

 many times and each time the effect was instantaneous. 



" At about 5.30 the swarai began to diminish, the males flying off singly into 

 the air. Very often a male would start off with a hesitating flight, and after 

 flying some distance and hovering about as if reluctant to leave, would again 

 return into the swarm. At last the swarm was reduced to three males which re- 

 mained for some time, and at the last a single male remained, continuing his evo- 

 lutions alone for fully three minutes, when, at 5.45, he too flew off. 



" A curious circumstance was the presence, on both occasions, of a swarm of 

 minute Chironomidfe in close proximity to the swarm of Anopheles. ]\Ir. D. W. 

 Coquillett kindly determined these as Ahlahesmyia pilosella Loew. While these 

 did not mingle with the swarm of Anopheles they were as close as they could be 

 without interference. Apparently the spot which the Anopheles had fixed upon 

 had the same attraction for them. This swarm seemed likewise to be composed 

 wholly of males. 



" It seems remarkable that the attitude taken by Anopheles in copulation, 

 end to end and facing in opposite directions, is identical with that of Culex 

 pipiens. This remarkable agreement is significant when the structure of the 

 tarsal claws is considered. In both forms it is practically the same and all the 

 claws of the female are simple. In both cases the legs are not made use of in 

 the copulatory act itself but only in the preliminary scuffle. Dr. H. G. Dyar has 

 found that Culiseta consohrinus* another form with simple claws and quite a 

 distinct generic type, takes the same position in copulation. It is fair to 

 assume that this is the mode of copulation in all the forms in which the female 

 has simple claws. On the other hand it appears that in those forms in which 

 the female has toothed claws the position in copulation is face to face, the pair 

 clasping each other. The writer can confirm Goeldi's observation that Stegomyia 

 calopus copulates in this manner. Dr. Dyar has observed the same method of 

 copulation in Aedes varipalpus Coq. One can not avoid the inference that the 

 difference in the structure of the claws is closely correlated with the mode of 

 copulation. . . ." 



Since the publication of the above article we have found that Curtis, in his 

 British Entomology, vol. 5, no. 210, quotes the observations of Haliday on the 



*=zCuUseta inornatus Will. 



