HORSEFLIES OF THE SUBFAMILY TABANINAE 13 
Diachlorus Osten Sacken, Mem. Boston Soc. Nat. Hist. 2 (pt. 4, No. 4): 47, 
1876; Ricardo, Ann. Mag. Nat. Hist. (7) 14: 356, 1904; Kréber, Arch. 
Schiffs u. Trop. Hyg., Bd. 32, Beihefte 2, pp. 35-86, 1928. (Genotype, 
Tabanus bicinctus Fabricius. ) 
Generic characters.—Small, slender, frequently yellow species; ocellar tubercle 
lacking; first antennal segment one and one-half to three times as long as 
greatest thickness; second short; third elongate, with five divisions, the first 
- division with scarcely any dorsal angle; second palpal segment moderate in 
thickness; cell Rs of wing open; wing usually marked with brown; fore tibia 
thickened. 
Key to the Nearctic Species of Diachlorus 
1. Base of cell Rs considerably suffused with brown; fore femur yellow on 
pasalphailigorsmoresi 2. as seo se te ae ee ferrugatus Fabricius, p. 13. 
Base of cell Rs hyaline; fore femur entirely black---__-_ badius Krober, p. 14. 
DIACHLORUS FERRUGATUS (Fabricius) 
(hiss 3, As) 
Chrysops ferrugatus Fabricius, Systema Antliatorum, p. 111, 1805. 
Tabanus americanus Palisot de Beauvois, Insectes recueillis en Afrique et en 
Amerique, p. 222, 1813-1820. 
Tabanus ferrugatus Wiedemann, Diptera Exotica, pt. 1, pp. 94-95, 1821. 
Diabasis aiaenia Macquart, Dipteres exotiques nouveaux ou peu connus, v. 1, 
pt. 1, p. 152, 18388; Walker, List of the Specimens of Dipterous Insects in 
the Collection of the British Museum, pt. 5, p. 271, 1854. 
Figure 38.—Antenna, front view of head, and palpus of (A) Diachlorus ferrugatus and 
(B) front view of head and palpus of Dicladocera finitima. 
? Diabasis varipes Rondani, In Baudi and Truqui, Stud. Ent. 1: 105, 1848. 
Dichelacera ferrugata Walker, List of the Specimens of Dipterous Insects in the 
Collection of the British Museum, pt. 1, p. 191, 1848. 
Chrysops approximans Walker, List of the Specimens of Dipterous Insects in 
the Collection of the British Museum, pt. 1, p. 198, 1848. 
Chrysops convergens Walker, List of the Specimens of Dipterous Insects in the 
Collection of the British Museum, pt. i, pp. 198-199, 1848. 
Tabanus rondanii Bellardi, Saggio di ditterologia messicana, pt. 1, pp. 68-69, 
1859. 
Diabasis ferrugata Osten Sacken, Mem. Boston Soc. Nat. Hist. 2 (pt. 4, No. 1): 
396-897, 1875. 
Diachlorus ferrugatus Osten Sacken, Smithsn. Mise. Collect. No. 270, pp. 55-56, 
1878; Ricardo, Ann. Mag. Nat. Hist. (7) 14: 359, 1904; Banks, Ent. News 
15 : 290-291, 1904; Kréber, Arch. Schiffs u. Trop. Hyg., Bd. 32, Beihefte 2, 
pp. 36-87, 1928; Bequaert, Jour. N. Y. Ent. Soc. 39: 552-553, 1931. 
Small, slender; yellow; wing with broad apical brown spot; base of cell Rs 
somewhat infuscated ; fore femur largely yellow. 
Female——Length 7-10 mm. Hye bare, blue green, with a curved, reddish- 
purple stripe extending from a short distance below top of frons around to 
lowest point of eye, and two triangles of same color, one with base on lower 
frons, the other with base on upper clypeus. Frons yellow, about six times as 
high as wide, the sides nearly parallel; basal callus a small, brownish, longitud- 
inal spot not touching eyes; median callus a very slender line from basal callus 
three-fourths of distance to vertex; subcallus yellowish. Antenna yellow orange, 
apically somewhat blackened by short pile; first segment about one and one-half 
