SOME ANNOYING PESTS OF MAN 337 



The black-flies of the North are S. venustum, S. vittatum, 

 and S. hirtipes. It is generally supposed and generally 

 said that the first species is the one particularly trouble- 

 some to man in the northern woods. This species ranges 

 from Maine to Florida and Texas and evidently has two 

 or three generations during a season. This would lead 

 me to think that S. venustum is not the biting species 

 in the Adirondacks, or else the first generation is com- 

 posed of biting individuals, while the females of the later 

 generations do not bite. The writer has spent two seasons 

 at Cranberry Lake in the Adirondacks from the 1st of 

 July to the 5th of September and has not been troubled 

 with black-flies. The inhabitants in the vicinity of Cran- 

 berry Lake say that they are not troubled with black- 

 flies after the middle of July. There is also a saying that 

 when the black-flies put on their white stockings the biting 

 is over. S. venustum is the species with white-banded 

 legs or, as they say, "white stockings." Moreover, 

 Needham,who has observed this species in the Adirondacks, 

 says, "It must be another, earlier species of black-fly 

 which makes all the trouble in the Adirondacks with its 

 bite ; for this one is quite peaceably disposed." On the 

 other hand, S. hirtipes occurs in the Adirondacks, is known 

 to be a vicious and persistent biter, and has only one 

 generation a year, which appears in May and June. It is 

 quite possible that this is the particularly annoying species 

 in the Adirondacks. 



Injuries by black-flies to man. — The injuries to human 

 beings by black-flies are, on occasion, very severe. The 

 effect of the bite of a black-flvis much more severe than that 

 of a mosquito. It is evident that the saliva injected into 

 the wound bv the flv has a serious effect both on the lower 



