1919] Hine: Genus Erax 109 



9. Wings hyaline, not unusually large bicolor Bcllardi 



Wings brownish, especially toward the apex; very large species, .grandis n. sp. 

 10. Mystax straw yellow with a few black bristles above, wings pale yellowish 



brown bimaculatus Bellardi 



Mystax black with a few pale bristles intermixed; wings fuscous, more 

 apparent towards the apex quadrimaculatus Bellardi 



Erax barbatus Fabricius. 



Length 13 to 20 millimeters. Male. All vestiture of the head white 

 to pale yellowish. Quite often a few black bristles in the mystax and 

 occasionally on the palpi. Thorax pale pollinose, not always of the 

 same shade, markings very obscure, anteriorly with short pile variable 

 in color, posteriorly with a number of black pale bristles. Scutellum 

 with sparse pale pile on the disc and a few black or pale bristles on the 

 margin. Femora black in ground color obscured by white pollen and 

 hair, apex of each tibia and whole of tarsi largely black, tibiae otherwise 

 pale yellowish, bristles of the legs variable from black to pale, wings 

 slightly yellowish, nearly hyaline, costa not dilated, anterior branch of 

 the third vein with a distinct stump variable in length in different 

 specimens, basal section almost in direct line with the cross vein at 

 the base of second posterior cell. Abdomen dorsally, first and second 

 segments pale pollinose, usually a rather small rounded blackish spot 

 on each side of the second; third, fourth and fifth largely black with 

 posterior margins and often median stripe pale pollinose; sixth and 

 seventh silvery. Hypopygium black. See Figures 2 and S. 



Female colored like the male, abdominal segments six and seven 

 colored like the preceding in most cases, but sometimes the segments 

 are nearly wholly gray pollinose, oviduct shining black. 



This species is the most widely distributed of any of the 

 genus. It ranges from Guatemala and Lower California to 

 Washington and New England and often is the first of the 

 genus taken in any locality within its range. 



The uniform color of the thorax without apparent markings 

 and the two rows of black spots on the abdomen make its 

 determination easy. Although the two longitudinal rows of 

 black abdominal spots are present in most cases there is varia- 

 tion, some specimens having these spots much reduced while 

 others have them enlarged until nearly the whole abdomen is 

 black. The two basal segments, however, most always are 

 uniformly gray and the other segments have at least a narrow 

 middorsal stripe and posterior border on each, the same color. 



The possibility of more than one species in the material 

 used has been considered but it does not appear possible to 

 find characters for satisfactory separation, so it is preferable 

 to include all in a single species. 



