160 MISC. PUBLICATION 305, U. 8S. DEPT. OF AGRICULTURE 
subcallus usually pollinose; frons rather wide; a stump vein, often rather long, 
from base of vein R.. 
Female.—Length 15-17 mm. Eye pilose, greenish blue, with three narrow 
purple stripes. Frons gray, about three and six-tenths times as high as width 
at base, somewhat widened above; basal callus black, subquadrate, touching 
eyes; median callus black, about same length, and usually narrowly joined 
to basal callus; ocellar tubercle small, yellowish brown; subcallus usually 
with gray pollen, but at times partially or entirely denuded. First two an- 
tennal segments reddish brown to gray, with black hair; third black, sometimes 
tinged with orange at extreme base; basal portion slender, dorsal angle slight 
and dorsal excision very shallow; annulate portion somewhat shorter than 
basal portion. Clypeus and genae gray, with mostly white hair. Second palpal 
segment stout at base and tapering to a point, creamy white. with concolorous 
and some black hair. 
FigurkH 78.—Antenna, front view of head, and palpus of (A) Tabanus hirtulus and (B) 
T. opacus. 
Mesonotum dark gray, with lighter gray stripes in usual pattern; prescutal 
lobe at least tinged with yellowish brown. Pleura, sternum, and coxae dark 
gray, with a mixture of black and whitish hair. Wing hyaline, the base of 
vein Rs usually with a stump which may be quite long. Legs black, the basal 
half of fore tibia and most of middie and hind tibiae orange brown, with 
cream-colored hair; hind tibial fringe mostly black. 
Abdomen above black, with three rows of gray spots, the median row con- 
sisting of small triangles not reaching length of tergites, the sublateral spots 
rather small, often tinged with brownish; venter gray, tinged basally with 
reddish brown. 
Male.—Eye densely pilose, the areas of large and small facets only weakly 
differentiated; second palpal segment stout, with mostly black hair. Color 
of body throughout agreeing with female. 
Type.—A female in the British Museum. 
Type locality —Washington. 
Distribution—W ashington and Alberta to Ontario and south to 
California, New Mexico, and Illinois. June 2 (Friday Harbor, 
Wash.) to August 14 (Logan, Utah). In the United States National 
Museum, 83 females, 2 males. 
The Zabanus opacus Coquillett of Hine is this species and not the 
true opacus. Hine later studied the type of hirtulus, and a specimen 
which he compared with the type fits the above description. Philip 
has suggested that 7. tetvicus Marten represents the form of this spe- 
cies in which the subcallus is denuded. This may well be so, but, 
since the Marten types are lost, it hardly seems desirable to make the 
change of name that would be necessary if tetricus were to be 
recognized. 
This is one of the abundant species of the Northwest. 
TABANUS OPACUS Coquillett 
(Fig. 78, B) 
Tabanus opacus Coquillett, in Baker, Invertebrata Pacifica, v. 1, pp. 21-22, 1904; 
Philip, Canad. Ent. 68: 154~155, 1936. 
Rather small; grayish brown, with three rows of pale spots on abdomen, the 
sublateral spots oblique; prescutal lobe reddish; femora black; ocellar tubercle 
