00 MISC. PUBLICATION 305, U. S. DEPT. OF AGRICULTURE 
long, slender, median callus; subcallus flat, brown. Antenna black, the third 
segment with a blunt dorsal angle and rather deep excision; annulate portion 
dark brown. Clypeus and genae brown, with dense brownish-black hair. 
Second palpal segment moderately long and slender, black, with black hair. 
Thorax dark brown, with black hair. Haltere brown, the extreme apex 
paler. Wing subhyaline, the costal cell and margins of all veins basad of 
furcation and apex of cell first M2 rather broadly margined with brown; vena- 
tion normal. Legs black, the empodium and pulvilli creamy white. 
Abdomen black, with black hair. 
Male.—Unknown. 
Type.—Female, United States National Museum No. 51968. 
Type locality —Huachuca Mountains, Ariz, 
TABANUS AEGROTUS Osten Sacken 
(Fig. 37, A) 
Tabanus aegrotus Osten Sacken, U. S. Geol. and Geogr. Survey Terr. Bull. 
3: 219-220, 1877; Williston, Kans., Acad. Sci. Trans. 10:139, 1887; Hine, 
Ohio Nat. 5: 234, 1904; Rowe and Knowlton, Canad. Ent. 67: 240-241, 1935; 
Philip, Bull. Brooklyn Ent. Soc. 31: 190, 1936. 
FIGURE 37.—Antenna, front view of head, and palpus of (4) Tabanus aegrotus and (B) 
T. wiedemanni. 
Rather large; entirely brownish black; wing nearly hyaline, unspotted. 
(Mountains of western North America.) 
Female.—Length 17-23 mm. Hye bare. Frons brown, about four times as 
high as wide, with parallel sides; basal callus flat, vertical, dull reddish brown 
to black, about three-fourths width of frons; median callus black or dark 
brown, broadly joined to frontal callus, gradually tapering above and reaching 
nearly to vertex; subcallus brown. Antenna black, the basal portion of third 
segment stout, with a prominent dorsal angle and a distinct dorsal excision ; 
annulate portion nearly as long as basal portion. Clypeus and genae dark 
brown to black, with brown hair. Second palpal segment black, moderately 
stout at base and usually tapering to a sharp apex. 
Thorax dark brown to black, with brown hair. Wing subhyaline, unspotted ; 
costal cell yellowish brown; cell Rs; somewhat narrowed apically. Legs nearly 
black, the hind tibial fringe well developed, black. 
Abdomen colored as thorax, rarely with a median row of smali whitish 
triangles. 
Male.—Coloration as in female. Line of differentation between areas of 
large and small facets not sharp, although usually the extreme difference in 
size is considerable; second palpal segment short and stout. 
Type—Female, Museum of Comparative Zoology. 
Type locality —California. | 
Distribution—Mountains from British Columbia to southern 
California and Utah. June 5 (Mount Wilson, Calif.) to August 18 
(Logan Canyon, Utah). In United States National Museum, 20 
females, 7 males. 
Tabanus aegrotus is near nigrescens Palisot, but lacks the spots on 
the wing and has a smaller, less shiny basal callus. 
