Ant. 4, REVISION OF THE FAMILY THEREVIDAE—COLE. 71 
PSILOCEPHALA TERGISSA (Say). 
Plate 6, fig. 50, and plate 7, fig. 66. 
1823. Thereva tergissa Say, Journ. Acad. Nat. Sci. Phila., vol. 3, p. 39. 
1828. Thereva corusca WIEDEMANN, Auss. Zw. Ins., vol. 1, p. 232. 
Male.—Length 9 mm. Face golden yellow; frons silvery white 
below, golden brown above, the pile very sparse and minute. First 
and second antennal joints yellowish, third yellowish at base and 
brown at tip, the style black. Occiput golden brown above, silvery 
white below, the bristles black. 
Thorax dark brown, with two darker vittae, the pile yellowish 
and sparse. Scutellum lke the thorax. Pleura with whitish pollen. 
Abdomen light brownish, semishining, with a silvery pollen above. 
Venter yellowish brown, with yellow incisures. The legs and wings 
are as in the female described below. 
Female.—Length 8.5 to 9.5mm, Resembling the male in many 
respects. The ocellar tubercle and upper half of the frons golden 
brown pollinose; just below the center, next each eye margin, around 
velvet black spot (fig. 50); just above each spot a triangle of silvery 
pollen; the portion between the spots golden brown, below this silvery 
pollinose to the base of the antennae. Face and upper occiput yel- 
lowish brown pollinose, lower occiput grayish white pollinose; post- 
ocular bristles black; pile of lower occiput white. Third antennal 
joint yellowish, brown at the base and tip, the style black; pile and 
bristles of first two joints black; third joint laterally compressed, but 
slightly wider than the first and longer than the first and second 
combined. 
Thorax, pleura, coxae, and scutellum yellowish or gray in ground 
color, with white pile. Mesonotum with four brown vittae and lateral 
brown spots; most of the pile reclinate whitish, a few erect, short 
black hairs. Scutellum with two marginal black bristles. Bristles 
of the thorax black. 
Abdomen brown, semishining; pile of first three segments short, 
reclinate whitish, beyond the third segment erect and black as 
usual; posterior margins of the segments yellowish, in some speci- 
mens the whole dorsum more or less yellowish; first segment gray 
pollinose. Stem of halteres whitish, the knob blackish brown. 
Femora yellowish or yellowish brown; tibiae, except apices, and base 
of tarsi yellowish, the remainder of the tarsi blackish brown. Wings 
whitish hyaline, the veins partly yellow and partly brown. (Fig. 66.) 
Type locality. —Eastern Florida. 
Type.—Not in existence. 
Distribution.—The 2 males and 10 females examined were from the 
following localities: Florida—Pensacola, October 11; Marco, April 
