HORSEFLIES OF THE SUBFAMILY TABANINAE 83 
Mesoscutum nearly black, with lines of reddish pollen and gray pile in usual 
pattern; scutellum sometimes margined with reddish; prescutal lobe, upper 
portion of pleura, and lateral portion of sternum reddish, the rest of pleura and 
sternum nearly black. Wing hyaline, the cross veins and fureation distinctly 
margined with brown; cell Rs somewhat narrowed apically. Legs reddish brown 
to black, the fore tibia pale on basal half, with white hair, black apically, the 
division distinct ; middle and hind tibiae black apically; hind tibial fringe well 
developed, white, except at apex, where it is black. 
Abdomen above black, tinged with reddish, with three rows of gray spots; 
median triangles rather narrow, extending whole length of segments; sublateral 
spots larger, oblique, touching hind margin on second and sometimes third 
segments, but not on others and not joined to median triangles along hind 
margin of segments; venter gray, Somewhat darker medianly. 
Male.—Hye densely pilose, the upper facets slightly larger than the lower 
ones, the line of differentiation not distinct. Hair of genae black, of pleura 
and sternum white, dense. Sublateral abdominal spots considerably larger 
than in female. 
Type.—Female, collection unknown. 
Type locality —Pennsylvania. 
Distribution.—Alberta to Nova Scotia and south to Colorado, Ar- 
kansas, and Georgia. June 4 (Atlanta, Ga.) to September 10 (Tren- 
ae N. J.). In the United States National Museum, 20 females, 7 
males. 
The larvae of this species may usually be found in the muddy banks 
of almost any stream or pond, their abundance in any locality greatly 
exceeding the number of adults that can be found. Whether this is 
due to a high mortality for the immature stages or to secretive habits 
in the adults is not known. 
TABANUS AMERICANUS Forster 
(Fig. 31) 
Tabanus americanus Forster, Novae Species Insectorum, centuria 1, p. 100, 
1771; Osten Sacken, Mem. Boston Soc. Nat. Hist. 2 (pt. 4, No. 4) : 457-458, 
1876; Hine, La. Agr. Expt. Sta. Bull. 98: 42-48, 1907; Snyder, Ent. Soc. 
Wash. Proce. 19: 141-145, 1917; Mosier and Snyder, Ent. Soc. Wash. Proc. 
20: 115-126, 1918. 
Tabanus plumbeus Drury, Illustrations of Natural History, v. 1, p. 103, pl. 44, 
NEB2AN GTS: 
Tabanus ruficornis Fabricius, Systema Entomologiae, p. 789, 1775. 
Tabanus limbatus Palisot de Beauvois, Insectes recueillis en Afrique et en 
Amérique, pp. 54-55, 1807. 
ee ening americanus Enderlein, Mitt. Zool. Mus. Berlin 11: 3887, 
1925. 
The largest Nearctic tabanid, brown, with wing hyaline and costal cell dark. 
Female.—Length 25-80 mm. Eye bare, unicolorous, brilliant green. Whole 
head orange yellow. Height of frons about four times width at base, slightly 
narrowed above; basal callus orange brown or dark brown, narrower than 
frons, higher than wide, tapering to linear median callus above, which reaches 
to upper third of frons or beyond; vertex gray, with black hair and a dark, 
often shiny triangle. Pile of clypeus and genae bright yellowish orange. 
Antenna uniformly orange; first two segments with black hair; third slender, 
with a very prominent, forward-projecting, dorsal process; annulate portion 
slender, shorter than width of basal portion. Second palpal segment orange 
to brown, elongate, slender, compressed, with short black hair. 
Mesonotum dark purplish or reddish brown, sometimes with faint lines of 
gray pollen. Pleura and sternum reddish brown, with orange or brownish 
pile, particularly a patch on epimera; tufts of yellowish-white pile above and 
below wing base and on postalar lobe. Wing hyaline, the costal cell and base 
strongly infuscated; cell R; slightly narrowed apically. Legs orange brown, 
a tarsi darker; hind tibial fringe well developed, orange brown to nearly 
lack. 
