88 MISC. PUBLICATION 305, U. 8. DEPT. OF AGRICULTURE 
Schwardt, Ann, Ent. Soc. Amer. 25: 631-635, 1932; Kréber, Rev. Ent. 4: 306, 
1934; Rowe and Knowlton, Canad. Ent. 67: 241, 1985; Schwardt, Ark. Agr. 
Expt. Sta. Buli. 332: 27-32, 1936. 
Tabanus niger Palisot de Beauvois, Insectes recueillis en Afrique et en Amer- 
ique, p. 54, 1807. 
Tabanus validus Wiedemann, Aussereuropaische zweifliigelige Insekten, vy. 1, 
pp. 113-114, 1828. 
Straba atrata Enderlein, Mitt. Zool. Mus. Berlin 11: 355, 1925. 
Stigmatophthalmus atratus Enderlein, Mitt. Zool. Mus. Berlin 11: 387, 1925. 
Large; black, with wing dark brown; frons broad; frontal callus transverse. 
Female.—Length 20-28 mm. Eye bare, dark purple or bronzy black, with a 
narrow jet-black band across middle and a broad band of same color below. 
Frons brownish or grayish, two to two and one-half times as high as wide, with 
parallel sides; basal callus shiny black, transverse, not quite so wide as frons; 
median callus an indefinite line above; subcallus somewhat swollen, shiny, black 
FIGURE 35.—Antenna, front view of head, and palpus of Tabanus atratus. 
or brownish. Antenna black; first segment not noticeably enlarged; third 
rather slender, with a prominent, slender, dorsal process, which projects forward 
somewhat; annulate portion about as long as basal portion beyond dorsal 
process. Genae rather shiny black, with rather sparse black hair. Second 
palpal segment black, moderately heavy, tapering to a rather blunt apex. 
Thorax, abdomen, and legs black. Mesonotum sometimes with a reddish 
tinge. Abdomen often pruinose. Wing almost uniformly dark brown. Cell Rs 
decidely narrowed at margin. Base of fore tibia sometimes whitish. 
Male—Area of large facets of eye extensive, the upper surface of eye flat- 
tened; small facets on lower third and the area extending along upper half of 
eye as a narrow margin. Body coloration as in female. 
Type.—Collection unknown. 
Type locality —America. 
Distribution —Massachusetts and Florida west to Ontario, Idaho, 
and New Mexico; Mexico. February 7 (Key West, Fla.) to October 
2 (Paradise Key, Fla.). In the United States National Museum, 84 
females, 41 males. 
This is one of the best known of the horseflies, although it has 
never been reported to occur in the great abundance characteristic 
of certain species. The larva was first described by Walsh (22) 
without his knowing what species he had. Hart worked out the 
complete life history. Bromley made a very complete study of the 
external morphology of the adult fly. 
The type of the genus Stigmatophthalmus Lutz does not seem to 
be congeneric with this species, and the division of the genus 7’abanus 
inte those with the eye facets in the male differentiated (Strada) 
and those with the eye facets uniform (7 abenus) does not seem 
desirable. This species resembles the Neotropical Zabanus erebus 
Osten Sacken, of which Astigmatophthalmus satanas Krober is, with 
vlad 
