28 BULLETIN 1218, U. S. DEPARTMENT OF AGRICULTURE. 



that sub-genus ; the discovery of the as yet unknown male will have to de- 

 cide it. 



Female. — Face and front yellowish-gray; cheeks with pale hairs; front with 

 short black hairs; a fringe of such hairs on the upper edge of the occiput. 

 Front broad (in most specimens; much narrower in others) ; frontal callosity 

 narrower than the front, rather small, and variable in shape ; usually another 

 black, shining spot above it. Palpi short, stout at base, pale yellowish or 

 yellowish-white, with black pile. Antenna 3 pale brownish-red : annulate por- 

 tion of third joint sometimes, but not always, black or brown. The black 

 ground-color of the thorax is partly concealed under a gray pollen ; vestiges 

 of longitudinal gray lines are visible anteriorly ; a pale golden, sometimes 

 whitish, appressed, rather scarce, pubescence, and black, erect pile clothe the 

 dorsum. Pleura? gray, with pale gray hairs. Abdomen in well-preserved 

 specimens with three rows of yellowish-gray spots, formed by an appressed 

 pubescence ; the triangles of the intermediate row large, occupying the whole 

 breadth of the segment ; the spots of the lateral rows are oblique, prolonged 

 laterally along the hind border of the segments (well-preserved specimens seem 

 rarely to occur ; in the worn specimens, the abdomen appears as grayish- 

 black, somewhat reddish on the sides of the first two segments, and with but 

 vestiges of the appressed yellowish-white pubescence and of the abdominal 

 spots). Venter uniformly yellowish-gray. Feet variable in coloring, pale 

 reddish-yellow with blackish (seldom pale) femora and tips of tibiae; tarsi 

 blackish with two posterior pairs paler at base. Costal cell and stigma more or 

 less tinged with brownish-yellow ; upper branch of third vein often, but not 

 always, with a stump of a vein. Length 12 — 13 mm. 



Hal). — Webber Lake* Sierra County, July 21. Twelve females. 



Although not so conspicuous as either T. punctifer or T. phaenops, 

 T~ insuetus is a hard biter and occasionally becomes numerous enough 

 in some of the higher mountain valleys to be troublesome to stock. 

 It confines its attack for the most part to the legs and abdomen when 

 attacking horses. 



The larvae are to be found without much difficulty in wet places 

 in the upper valleys, in the top soil and humus at the base of grass 

 roots. Abundant as the larvae were in such situations, the eggs of 

 this species have never been seen in nature, nor did the authors suc- 

 ceed in inducing ovipositions in rearing cages. 



Quite a number of individuals of this species were reared from the 

 larva to the adult stage in the laboratory. The pupal period was 

 found to vary from 15 to 22 days. 



Description of Full-Grown Larva. 



Full-grown larva (fig. 16, B; PI. Ill, D) 21 to 22 millimeters long, yellowish 

 white. Dorsal and ventral aspects of all thoracic and abdominal segmenls 

 smooth and shiny. Sides of all segments, except prothorax, mesothorax, and anal 

 segment, finely striate. On each lateral aspect of mesothorax are two deep lon- 

 gitudinal lines (not continuous on prothorax but showing more faintly on meta- 

 thorax). Sides of prothorax smooth and shiny. Propodia arranged much the 

 same as in Tobanus punctifer, not very prominent in living specimens, clothed 

 with fine yellowish hairs which can hardly be called bristles. 



Anal segment robust. Anus surrounded by an opaque surface, bearing fine 

 yellowish pile. From each side of the anus extends dorsally a slight streak of 

 opaque which divides just before reaching the dorsal surface into two branches, 

 one extending posteriorly and the other dorso-anteriorly. Siphon very finely 

 striated, extending barely beyond anal segment. 



Description of Pupa. 



Pupa (fig. 14. C, D; PI. Ill, G) 13 to 15.5 millimeters long. Width of thorax 

 2.5 to 3 millimeters. Color light yellow with brown spots on head and thorax. 



Head region between bases of palpal sheaths rugose. Back of this two slightly 

 elevated and rugose areas one at each side of median line. Still farther back 



