lO CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D. Ser. 



9. Hercostomus impudicus, sp. nov. 



Plate I, Figs. 11-13. 



Male. Length 3 mm.; length of wing 2.5 mm. Proboscis and palpi small, 

 yellowish, the former edged with hairs. Face considerably narrowed below, 

 covered with thick, silvery white dust, and with a groove-like depression 

 running down its middle. Antennae entirely black; first joint rather slender, 

 distinctly hairy on its upper surface; second joint broad, covering much of 

 the base of the third joint on the inside; third joint large, about twice as long 

 as broad, pointed, with straight dorsal edge bearing the black, scarcely 

 pubescent arista near its middle. Ventral contour convex. Postocular cilia 

 pale. Front very broad, like the thorax and scutellum, thickly covered with 

 grayish brown dust, so that the metallic ground-color is scarcely perceptible. 

 There are two distinct rows of acrostichal bristles and five large bristles in 

 each inner dorsal row. Humeral bristles well developed. Scutellum with- 

 out hairs, but with a pair of robust mesial and a pair of minute lateral bristles. 

 Abdomen greenish coppery, brighter than the thorax; hairs and posterior 

 edges of the segments black. Hypopygium very large, subsessUe, black, 

 dusted with white, inflected under the abdomen, which it nearly equals in 

 volume. Penis and penis-sheath very large and prominent, the latter long 

 and club-shaped, terminating in a prominent black spine anteriorly. Each 

 of the large, pale lamellae is split into three linear processes fringed with long 

 black bristles. The ventral or uppermost process (in the natural, flexed posi- 

 tion of the hypopygium) is curved and broadened at its free end where it is 

 provided with incurved, short black teeth. On its outer surface, for some 

 distance towards the base, it bears long and rather delicate pointed bristles. 

 The bristles on the two other processes of each lamella have truncated 

 broadened tips. Pleurae and coxae covered with gray dust; middle and hind 

 coxae tipped with yellow; fore coxae yellow except at their bases and bearing 

 some prominent black bristles on their anterior surfaces. Legs plain, yel- 

 low. Fore and middle tarsi from the tip of the first joint, tips of hind femora 

 and hind tibiae and the whole of the hind tarsi, black. All the tibiae bear 

 prominent black bristles on their outer surfaces. First joint of hind tarsi 

 without bristles, shorter than the succeeding joint. Wings somewhat black- 

 ish, slightly narrowed towards the base, with black veins. Third and fourth 

 veins close together and very gradually converging towards their insertion in 

 the costa, the latter ending distinctly before the tip of the wing. Posterior 

 cross-vein before the middle of the wing and about one-third the length ol 

 the distal segment of the fifth vein, which reaches the posterior margin. 

 Halteres and tegulae yellow, the latter with black cilia. 



Female. Length 3 mm.; wing 2.5 mm. Face distinctly broader than that 

 of the male, but covered with the same silvery white dust. Third antennal 

 joint of the same shape but much smaller than that of the male. Coloration 

 of body, wings and legs like that of male except that there is much pale dust 

 along the sides of the venter. Ovipositor extruded, terminating in two 

 upturned points, each armed with three black teeth. 



One male and one female taken near Monterey, Calif., 

 during July, 1896. 



