10 BTJUJ3TIN 1218, U. S. DEPARTMENT OF AGRICULTURE. 



TABANUS PUNCTIFER Osten Sacken. 



Description of Adult. 



Tabanus punctifer (PI. I), popularly known as the big black 

 fly, is the largest fly commonly found in the Western States. Its gen- 

 eral appearance is black, with the top of the thorax yellowish white. 



The species was first described by Osten Sacken in 1875 {11), and 

 because the publication is not generally available the author's de- 

 scription is quoted here in'full : 



Male and female. Head ( $ ) large, with distinctly separated large and small 

 facets; front ( 9 ) broad (broader than in T. nigrescent) ; frontal tubercle large, 

 somewhat ill defined in outline and rather flat ; antenna? black, projecting angle 

 of the third joint rectangular; face brownish; palpi black. Thorax and scutel- 

 lum, above, whitish or yellowish white, in consequence of a dense pollen, covered 

 by a pubescence of the same color; pleurae, pectus, abdomen and legs black, or 

 dark brown; front tibise white at the base for more than one-third of 

 their length. Wings brownish, especially on their proximal half; costal 

 cell brown ; a faint brown cloud on the crossvein at the base of the second pos- 

 terior cell, which is not prolonged on the crossvein at the base of the third 

 posterior cell ; a dark brown round cloud at the bifurcation of the third vein. 

 Length. $, 19 mm.; $, 19-20 mm. * * *. 



This species is not unlike T. stygius Say, but is a little smaller, and easily 

 distinguished by the white color of the base of the front tibiae, the blackish or 

 brownish, and not ferruginous brownish, wings, the absence of distinct white 

 lines on the thorax, etc. The head of the male is much larger than in T. 

 nigrescens, and the large facets occupy much more surface. 



Unfortunately the males (PL I, A) are seldom seen in nature and 

 are hard to capture. A good number were reared from larvae, and 

 these males differ markedly from the description given by Osten 

 Sacken in the color of the dorsal vestiture. The dorsum of the thorax 

 of the male, instead of being clothed entirely v ith yellowish white, 

 has only a margin of that color, about 1.6 millimeters wide, surround- 

 ing a central area of black. This black spot appears in strong con- 

 trast with the whitish margin and is a very striking sexual distinction. 



Distribution. 



Osten Sacken gives the following: 



West of the Rocky Mountains ; Utah, Sonora, Calif., etc. ; also Colorado 

 (G. Ridings) ; seems to be a common species. 



Specimens have been taken at Hunt, Ariz. ; El Centro, Bishop, 

 Bridgeport, Topaz. Chico, and Alturas, C^alif. ; and Deeth, Love- 

 lock. Reno, and Carson City. Nev. The junior author has seen 

 them in eastern Montana at Powderville, but has not collected them 

 there. They were quite abundant in Antelope Valley and along 

 the east side of the Sierra Nevada Mountains north of Bishop, 

 Calif. In 1916 they were reported to have been exceedingly abun- 

 dant at Wellington, Nev. 



On account of less abundance, T. punctifer is considered of less 

 economic importance than T. phaenops. 



Abundance. 



From reports and observations, Tabanus punctifer was more 

 abundant in the summer of 1916 than during the three years fol- 



