120 PROCEEDINGS OF THE NATIONAL MUSEUM. VoL. 62. 
THEREVA HIRTICEPS Loew. 
Plate 10, fig. 126, and plate 12, fig. 166. 
1874. Thereva hirticeps Lorw, Berl. Ent. Zeit., vol. 18, p. 382. 
Male.—Length 9.5 to 12.5mm. Ground color of body largely black. 
Frontal triangle yellowish pollinose, the upper margin narrowly 
black; a line of black pile on the frons next the eye margin, most 
of the frontal pile yellow. Face gray pollinose with dense whitish 
pile. Antennae black, the base of the third joint may be reddish; 
' first joint about as long as the third, yellow pilose with black bristles; 
style short. Some black pile on the cheeks below the eye. Occiput 
largely gray pollinose, the upper part yellowish; pile below whitish, 
on the upper part golden yellow. A shining black line on the face 
from the base of the antennae to the oral margin. 
Mesonotum shining black except for two yellowish vittae, widely 
separated, slightly divergent anteriorly and reaching as far as the 
prescutellar bristles posteriorly; in some specimens the lateral margins 
of the mesonotum are thinly grayish pollinose. Pile of the disk of 
mesonotum erect and blackish, around the lateral margins yellowish, 
dense over the wing base. Scutellum shining black, with long erect 
yellow pile, four marginal black bristles, and occasionally a few black 
pile. Pleura gray pollinose, largely whitish pilose, with a yellowish 
tinge to the pile before the halteres and wing base. Stem of the 
halteres yellow, the knob blackish brown. 
Abdomen largely shining black, the posterior corners of: segments 
one to six brownish yellow, the seventh segment and genitalia brownish 
yellow. Posterior margins of second to sixth segments bright yellow, 
with reclinate yellow pile on the second to fifth; sides of the first to 
fifth long erect yellow pilose; dorsum of the sixth, seventh, and geni- 
talia black pilose. Posterior margins of second to sixth segments of 
venter bright yellow, the posterior halves of the same ventral segments 
brownish yellow, the basal part black. Pile of the venter yellow, 
including that below on the genitalia. Basal half of femora black, 
the apical portion, tibiae except apices, and base of tarsi reddish 
brown; tips of the tibiae and most of the tarsi black. Bristles of 
legs black. Pile of hind femora almost all tomentumlike and black, 
on the front femora mixed black and white, long, and erect on the 
outside and below, all black on the apical third. Veins at base of 
wing yellowish, black beyond; cell M-3 closed and short petiolate; 
stigma blackish brown; costal cell yellowish, the rest of the margin 
of the wing smoky gray, as are the clouds on the cross veins; central 
portion of the wings largely whitish hyaline. 
Female.—Length 10.5 to 13mm. Closely resembles the male, with 
the usual sexual differences. Frons and vertex yellowish pollinose, 
the shining black callosity reduced to a band touching the eye mar- 
