132 MOSQUITOES OF NORTH AMERICA 



Scott, Arkansas, has observed the same habit in Mcgarhinus septentrionalis. 

 He took a large number of males of this species upon a certain vine of poison ivy 

 (Rhus toxicodendron) and always upon this one plant ; none could be found else- 

 where. Such bushes are undoubtedly places of rendezvous in connection with 

 the mating-habit. 



Many species of Culicidse, on account of their specialized mating-habits, can 

 not be bred in captivity. The yellow-fever mosquito, the mating-habits of which 

 are discussed in another chapter (p. 275), can be bred successfully for a num- 

 ber of generations in comparatively small receptacles. Dr. Dyar has bred two 

 generations of Aedes atropalp^is in a quart jar containing a small quantity of 

 water. 



ABUNDANCE OF MOSQUITOES. 



In our treatment of the subjects of the migrations of mosquitoes, of their 

 carriage by wind, of far northern mosquitoes, and of early accounts of mos- 

 quitoes, we give many instances of mosquito abundance, and there will be men- 

 tioned here only certain recent observations. We have just discussed how at 

 times mosquitoes may be found gathered in concrete swanns for sexual purposes 

 and these swarms are appropriately considered under mating-habits. In so far, 

 however, as they are an indication of unusual abundance of mosquitoes they may 

 be mentioned here. 



Theobald briefly describes a few swarms, probably of this character, as follows : 



" Occasionally cloud-like masses of various Culices are seen. I remember 

 twice having noticed dense swarms of them in the fens; in both cases the in- 

 sects were male and female C. cantans. So abundant were they that the air was 

 quite darkened by them. These insect-clouds were constantly moving up and 

 down about ten to twelve feet above the ground. At times the noise they pro- 

 duced could be heard a quarter of a mile off, then it would suddenly cease for 

 some time and commence again. 



" Mr. W. W. Smith records a case in New Zealand where ' a train passed 

 through a wall of mosquitoes three-quarters of a mile in length, twenty feet high, 

 and eighteen inches thick.' This abnormal swarm was composed of Culex 

 ( Uranotwnia) argyropus Walker. 



******** 



" During the present year I had reported that dense masses of gnats were seen 

 along the Downs near Wye, appearing like columns of smoke in the valley, 

 rising and falling. I did not see this, but visited the Down-sides the next day 

 and found great numbers of male C. pipiens about in the evening, dancing in 

 little clouds where they were sheltered from the wind." 



" Romolo Gessi Pascha, in his book ' Seven Years in the Soudan,' p. 47 

 (1892), speaks of ' myriads of mosquitoes which obscured the air ' at Meshra-el- 

 Rek. If we go to the Arctic regions we get similar phenomena, for Dr. Lugger 

 informs Professor Howard that Dr. Emile Bessels, of the Polaris Expedition, 

 was obliged to interrupt his work in Davis Straits (latitude 72° N.) on account 

 of the multitude of mosquitoes." 



The above notes on Culex pipiens clearly refer to swarms of males such as 

 have been described under mating habits. This may also be the case with the 

 above-mentioned swarms of Aedes cantans and Uranotcenia argyropus, but there 



