HORSEFLIES OF THE SUBFAMILY TABANINAE 115 
apically ; hind tibial fringe entirely black; tarsi dark orange brown to black, 
the fore tarsus darkest. 
Abdomen above orange brown, somewhat darkened apically; a median row 
of white or yellowish triangles on tergites 1-5 or 6; on tergite 2, at least, 
usually a median black spot in front of triangle; hind margins of tergites 
with narrow yellow bands, slightly widened laterally; venter orange brown, 
with paler incisures and sometimes the sternites blackened along anterior 
margin. 
Male.—Area of large and small facets of eye distinctly differentiated, the 
extent of the large facets somewhat variable but usually covering little more 
than half of eye and with a rather broad band of small facets along hind 
margin. Second palpal segment nearly black, truncate apically. Pale hair of 
body more yellowish, with relatively little pale hair on legs. Fore tibia only 
slightly paler basally. Coloration of rest of body essentially as in female, 
the abdominal triangles varying considerably in size. 
Ficurn 54.—Antenna, front view of head, and palpus of (4) Tabanus sulcifrons and 
(B) T. abdominalis. 
Type.—Female, originally in the Bigot collection, perhaps now in 
the British Museum. 
Type locality—Baltimore. 
Distribution—Ilowa to New York and south to Oklahoma and 
Florida. May 10 (Columbus, Ohio) to November 15 (Baton Rouge, 
La.). In the United States National Museum, 266 females, 70 males. 
For many years Tabanus sulcifrons, T. exul, and T. variegatus have 
been considered to be distinct species or, in the case of exul at least, 
synonymous with abdoméinalis Fabricius. As pointed out under the 
latter species, abdominalis is quite distinct and should not be confused. 
This leaves a somewhat variable species, divided by Osten Sacken into 
three. One, which he described and named 7abanus tectus, he later 
found to be a synonym of 7’. sulcifrons Macquart, after studying the 
type of the latter. In this the abdominal triangles are large and broad 
and the large facets in the eye of the male are reduced in number, 
occupying only the upper portion of the eye. Another, described by 
Osten Sacken and named 7’. exul, has small abdominal triangles and 
a more extensive area of large facets in the male eye. The third, 7. 
wariegatus F., has the discal portion of the wing distinctly whitish. 
The writer has studied a large number of this species, involving both 
sexes of all three forms, and cannot see that any of the above-men- 
tioned characters are sufficient even to differentiate varieties or races. 
They do not sort out geographically, and intergrade so completely in 
any given area that there appears no excuse for separating them. 
This is the commonest horsefly in the vicinity of Washington, 
D. C., in midsummer and early in the fall. Garman, under the name 
of 7. exul, described a serious outbreak of them in Kentucky in 1910. 
