66 
THE BUFFALO-GNATS, OR BLACK-FLIES, OF THE UNITED STATES. 
[A synopsis of the dipterous family Simuliide. ] 
By D. W. CoQquiLLETrt. 
The dipterous family Simuliide contains but the single genus 
Simulium, of which the black-fly of the North and the buffalo-gnat of 
the South are well-known examples. They outrival the mosquito in 
their bloodthirsty propensities, poultry and even domestic animals 
sometimes losing their lives from their attacks. 
The black-fly of the North is the Simulium venustum Say, of which 
S. molestum Harris and 8S. piscicidium Riley are synonyms. It is not 
- confined to the North, however, but ranges southward as far as Bis- 
cayne Bay, Florida, and is found in the other Southern States, extend- 
ing westward to California. The larve of this species were formerly 
supposed to cause the death of young trout, but this accusation has 
since been disproved. 
The life history and habits of two other species, the Southern buffalo- 
gnat and the turkey-gnat, have been very thoroughly investigated by 
this Division, and a full account was published in the annual report of 
this Department for the year 1886. Neither of these species is con- 
fined to the South, both ranging as far northward as New Hamp- 
shire and Massachusetts. The food of the larve consists chiefly of 
microscopic Crustacea. 
In their relations with man, the most annoying species are S. venus- 
tum, the black-fly of the north woods, and S. invenustum, the buffalo- 
gnat of the South. There is at least one authentic record of the death 
of a human being through the attacks of the latter species. Dr. How- 
ard has called attention to the fact that although S. invenustum breeds 
abundantly in Rock Creek, near Washington, D. C., it is not known to 
bite human beings in this vicinity. Moreover, he informs me that the 
Same species, in May and the early part of June in wet seasons, occurs 
abundantly in portions of the Catskill Mountains, and that, although it 
is very annoying by flying about the face and crawling over the skin, 
it rarely bites. Dr. Howard has also studied the habits of S. pictipes 
at Ithaca, N. Y., and has recorded some observations on the larvie and 
egg-laying (the latter having been made by Professor Comstock) of this 
species in Insect Life, Volume I, pages 99-101. He says that this species 
also, although its larve occur in enormous numbers in the swift-running 
rock streams about Ithaca, does not,in the adult stage, seem to bite 
human beings.! 
1The most complete series of observations which has been made upon any species 
of Simulium, aside from those.recorded in the annual report of this Department for 
1886, upon the buffalo-gnat of the southwest, was made during 1889-90 by Miss 
R. O. Phillips, a student in the laboratory of Prof. J. H. Comstock, at Cornell Uni- 
versity. The results of Miss Phillips’s observations were embodied in her graduat- 
ing thesis, which has never been published. Professor Comstock has permitted the 
writer to examine the thesis and to extract the following facts: 
The species studied was Simulium pictipes Hagen. The adult occurs near Ithaca in 
