SIMULIUM, OR BUFFALO GNATS. 



Hon. NORMAN J. COLMAN, 



Commissioner of Agriculture: 



SiR: I herewith transmit the results of my- observations upon the species of Si- 

 mulium, infesting the country adjacent to the Mississippi River, from Missouri 

 southward to the Gulf of Mexico. These insects are generally known under the 

 common appellation of Buffalo gnats, Bull gnats, and Turkey gnats, and while, so 

 far as known the bites of only the first result fatally to horses, mules, and cattle, 

 the others combine with them in the destruction of sheep, swine, and other small 

 animals. 



The habits of all of the species of Simulium, herein considered, are, so far as 

 known, very similar, and as the species are not generally distinguishable to the 

 ordinary planter, Iv have thought best to refer to all of them under the general 

 term, Buffalo gnats, although, technically speaking, this term applies to only S. 

 pecuarum, Rileyl Other species consist of S. meridianole, Riley, and two or three 

 varieties yet to be described. 



Respectfully submitted. 



F. M. WEBSTER. 



LAFAYETTE, IND., October 25, 1887. 



BUFFALO GNATS. 



Habitat. All species of Simulium, infesting the country visited 

 by me, breed in running water, and hence inhabit only the swiftest 

 portion of small or medium-sized streams flowing through alluvial 

 regions. Streams flowing through hilly country dp not appear to 

 be congenial to their nature, although the current may be much more 

 swift and broken into shoals and ripples. Sluggish-flowing portions 

 of streams, lakes, lagoons, and swamps are not known to produce 

 these gnats, nor are they supposed to infest the waters of the Missis- 

 sippi River itself. 



The principal breeding grounds of Buffalo gnats, in the Mississippi 

 Valley, are situated between New Madrid, Mo., and the mouth of the 

 Red River in Louisiana. In the. latter State they are mostly con- 

 fined to the region between the Washita and Mississippi, exclusive 

 of either of these streams. In Arkansas they seem to be confined 

 chiefly to the St. Francis, its tritmtaries, and to those streams whose 

 sources are between the Mississippi and Bayou Bartholomew. The 

 Yazoo country, in Mississippi, suffers severely during some years, 

 but I found no evidence which would warrant that locality being at 

 present included in the chief habitat of these gnats; and the fatality 

 caused is nearly if not wholly due to the immense bands of these 

 insects which are blown by; the winds across the river from Louisi- 

 ana and Arkansas. This is especially true of northern Mississippi 

 and west Tennessee, and really restricts the habitat of the pest to 

 the country along the west side of the "Father of Waters," and 

 limited from north to south as previously stated. That an insect, 

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