126 MOSQUITOES OF NORTH AMERICA 



bushes, sign-posts, or even heads of grass, but others where the swarms hovered 

 over paths through fields, or spots of different color but not elevated above the 

 surroundings. The swarms over spots on the ground in all probability belong 

 to different species from those attracted to prominent objects. Radl confesses 

 that he made no attempt at close determination of the insects under observation 

 and it is evident that he had no conception of the number of forms of similar but 

 distinct habits that he might have before him. In consequence his statements 

 are far too general and much that might have been used for or against his con- 

 tention has escaped him. 



" Little as we yet know of the subject, it will be well to state right here that, 

 even within the Culicidse, there is not only a marked diversity in the mode of 

 swarming of different species, but that there are many forms which do not 

 swarm at all. In the case of the almost exclusively house-inhabiting Stegomyia 

 calopus, as Goeldi has sho^vn, there are no such swarms as in Culex proper. The 

 males congregate in little groups of 15 or 20, hovering over the corner of a 

 cabinet or other prominent object, and pounce upon the females that come within 

 range. I can add that copulation frequently takes place when there is no evi- 

 dence of even such weak swarms. It sliould be noted that in Stegomyia copula- 

 tion takes place during the brightest part of the day. On the other hand I have 

 upon two occasions observed small swarms of Stegomyia (presumably males) 

 hovering over the heads of persons, in both cases shortly before sunset. Once 

 this occurred upon the hotel veranda at Cordoba, Mexico, and again in the street 

 at Acapulco, over the heads of passers and keeping along with them. In this 

 case the meaning of the swarms would be hard to interpret. 



" Upon a recent trip to the west coast Dr. H. G. Dyar found a pair of Culiseia 

 consohrinus * in copula, resting on the under side of a board. This observation 

 shows a wide departure from the short copulatory act of Culex and Stegomyia. 



" The crab-hole inhabiting Deinocerites cancer swarms during the short twi- 

 light period just outside the crab-holes and copulation takes place then. 



" Goeldi has given a vivid account of the swarming of the common house-- 

 mosquito of Para which he designates as Culex fatigans.'\ Swarming takes place 

 indoors when it is nearly or quite dark and there are separate swarms of males 

 and of females. Such peculiar mating-habits surely indicate a distinct species. 

 In the case of our Culex pipiens the males are never found in houses — unless, 

 indeed, they happen to come from larvae developed indoors. 



" Mr. E. A. Schwarz has kindly placed at my disposal his observations made 

 on a species of Culex, probably the Culex cuhensis of Bigot,| at Cayamas in 

 Cuba. The swarming occurred in the house, always on the side away from the 

 sun, and when it was almost fully dark. The mosquitoes could only be seen 

 against the sky, when between the observer and the open doors and windows and 

 close observation was impossible under the circumstances. However, the swarms 

 in this case were made up of both sexes and copulation freely took place. A cap- 

 ture of 60 specimens from such a swarm contains 44 males and 16 females." 



In a later paper entitled " The Swarming of Anopheles punctipennis Say " 

 (Psyche, February, 1907), Knab published some novel observations on the 

 swarming of the species mentioned. This is quoted : 



" Upon October 7 and 14 the writer observed the mating habits of Anopheles 

 punctipennis and as, up to the present, nothing appears to have been made known 



*:=CuHseta inoniatus. 



^ = Culex quinquefasciatus. The passage will be found in translation in the systematic part 

 of this worli. 



1 The specimens on which the observation was made have since been identified as Culex 

 quinquefasciatus. 



