THE CANADIAN ENTOMOLOGIST. 199 



5 same as the $ , except that the pollen on the upper part of the front 

 is more yellow, and the eighth and ninth abdominal segments are shining 

 yellow, posterior margins of the other segments also more or less yellow. 



Length, 8 to n mm. Southern California. Eleven males and four 

 females, in April and May. 



Thereva daplicis, n. sp. £ black, the femora, tibiae, tarsi, except at 

 apex, and the hypopygiurn, yellow. Head gray pollinose, the pile wholly 

 yellowish-white, that of the vertex, bristles in upper part of the occiput 

 and on the antennae, black ; third antennal joint as long as the first and 

 only slightly wider, style one-fourth as long as the third joint. Pile of 

 thorax mixed black and yellowish-white, the bristles black ; pile of pleura 

 white, that on the scutellum more yellowish, the four bristles black. Pile 

 of abdomen yellowish-white, that of the venter white, of the femora mixed 

 black and white, of the tibiae and tarsi black ; bristles of legs also black. 

 Wings grayish-hyaline, the veins largely brown and indistinctly bordered 

 with brown, stigma dark brown, fourth posterior cell closed and short 

 petiolate. 



9 same as the £ , with these exceptions : Pile of front largely black, 

 its pollen yellow ; in middle of front are two transverse shining black 

 spots separated from the eyes by a pollinose interval nearly equalling the 

 length of the second antennal joint. Posterior margin of each abdominal 

 segment, except the first, yellow, including the greater portion of the last 

 three segments ; base of the third, fourth, fifth and sixth segments, and 

 the whole of the following ones, shining ; pile of the fourth and following 

 segments both dorsally and ventrally erect and black. 



Length, 9 to 13 mm. South Dakota (Aldrich), Montana (Morrison). 

 One male and two females. 



Thereva otiosa, n. sp. $ black, the knob of the halteres, and pos- 

 terior margins of the second and third abdominal segments, white, tibiae, 

 except at apex, and base of tarsi, yellow. Head white pollinose ; that 

 on upper part of front narrowly black, on the vertex grayish-black ; pile 

 of entire head, except the black pile of the vertex, white ; bristles of 

 upper part of occiput and on the antennse black. Third joint of antennae 

 five-sixths as long as the first and slightly narrower, style one-fourth as 

 long as the third joint. Thorax grayish-black pollinose and marked with 

 two narrow whitish pollinose vittae, the lateral margin also whitish pol- 

 linose ; pile of thorax mixed black and white or yellowish, the bristles 



