40 
pass certain places in them, out dart the tormentors, and the ani¬ 
mals attacked can only save themselves by running to high places' 
exposed to the full rays of the sun. The gnats, following the ani¬ 
mals for some distance, leave as suddenly as they appeared, and 
hide themselves again in the thickets. In the cities they appear 
suddenly with certain winds, chiefly with those blowing from the 
south, southeast, and west, and usually disappear again with winds 
blowing from the opposite direction."* 
* 
Fig. 9. The Buffalo-gnat, Simulium fecuarum, 
adult fly. X 10. (From H. Garman.) 
S. pecuanim Riley (Figs. 9 and 10).—This species, commonly 
called the buffalo-gnat, is a companion to meridioiiale —reported, 
however, to breed mainly in the large rivers, while meridioiiale 
is commonly a small-stream species. The two become mingled in 
swarms when abundant and have similar habits, pecuanim being 
the larger and the more bloodthirsty of the two. It is credited 
to this state by Aldrich in his “Catalogue of North American 
Diptera," but has not been taken by us in Illinois, our collections 
of Simulium not having been made, in fact, in those parts of the 
state where it is most likely to occur. Its general range is similar 
to that of the turkey-gnat, altho, like that species, it is essentially 
^Report of the Entomologist, U. S. Dept. Agr., for the year i3S6, pp. 
496-497. 
