26 
T. bromius, and maculicornis. Of the smaller Tabanidz must be mentioned Hema- 
topota pluvialis and Chrysops relictus and Ch. cewcutiens. 
Of the author’s observations in regard to the habits of various species only the 
following may be mentioned: The Hematopota pluvialis apparently does not like 
objects of a white color. In its attacks upon animals as well as in selecting a place 
of rest this insect makes use mostly of objects of a dark color. Thus, in white 
clothes, I always was less subject to its attacks than when wearing a gray or dark 
suit, and the same was true even before a rain when these insects are most unbear- 
able and least particular. White horses, according to my observations, suffer com- 
paratively less than those of other colors, especially black ones. 
Water and arboreal plants are the chief conditions of the existence and multipli- 
cation of the Tabanidie; where these conditions are absent no Tabanidz are 
observed. : 
Scarcely anywhere is man engaged in actively combating the Tabanidie; all the 
measures thus far applied are merely in the nature of palliatives. Of the latter per- 
haps the most in use is fish fat (blubber?) applied to the animals as a grease. Not 
only is man powerless in his fight against these insects, but in nature also as far as 
we know they appear to have few enemies. In North America a parasite has been 
discovered which destroys the eggs of the Tabanidze. This parasite belongs to the 
Hymenoptera and lays its eggs in those of the Tabanidze. In Russia as a dangerous 
enemy of the Tabanidz appears the fly-eating wasp, Bembex, which raises its larvee 
at the expense, among other insects, of the Tabanide. However, this wasp does not 
confine itself to the Tabanide; it is very omnivorous and seizes various Diptera, but 
in the presence of Tabanide prefers the latter. Soaring in the air at almost a man’s 
height, with a fine characteristic buzz, the Bembex throws itself with the velocity 
of a flash upon the Tabanus, seizes it, and carries it into its burrow. It is probable 
that the scarcity of Tabanidz in some places, apparently very favorable for their 
existence and multiplication, is due to the presence of the fly-eating wasps which, 
to be sure, in their turn, suffer from their parasites (the wasp Parnopes and the fly 
Miltogramma). 
Our extremely limited knowledge of the life and properties of the Tabanide 
offered very little promise of discovering a convenient means for their destruction, 
when in the summer of 1898, while riding in a locality very rich in Tabanide, I 
decided to take up this question. By observation I soon discovered certain habits 
of these insects which render their destruction a very simple matter. 
My observations in this connection were made at a northern latitude (in the neigh- 
borhood of Paolosk), and therefore related to a small number of species of Tabanide ; 
but these species are very widely distributed and very rich in individuals. The 
Tabanidze about which I speak seem to experience a strong desire for water, which 
leads them to frequent places where it can be had. Observing these insects, one can 
not fail to notice how they collect in particular places on the so-called dances of the 
males, when the latter, soaring in the air at one point, suddenly fly to one side and 
continue the same maneuver at another point. Some places appear to be especially 
liked by them, and there they are sometimes found in such numbers that it is difficult 
to pass them without receiving several stings. Careful observations have shown 
that such favorite places of the Tabanidz are distinguished by great humidity, and 
usually have one or more pools wheu such on higher places have already dried up. 
Such humid spots in the clearings amid the woods and in the neighborhoed of wide, 
open roads in the woods are veritable nests of the Tabanide. Hither they come 
from over a considerable area of the woods, and thence they again fly away in all 
directions. If we watch such a pool, we soon notice that both males and females of 
the Tabanide come to it constantly, lower themselves quickly to the surface of the 
pool, and taking some water with the proboscis, fly away again. The contact of the 
Tabanus with the water does not present any danger for the insect, as only a part 
of the lower surface of its body touches the surface of the water, so that the Tabanus 
is not even wetted by the water, owing to thick down on the lower surface of the 
