52 Bulletm of the Brooklyn Entomological Society Vol. XII 



Described from a female specimen, collected in Colorado. It 

 can readily be separated from labeculata by its larger size and 

 the much larger areolae of costal area of the elytra; the two 

 species, labeculata and coloradensis, are equally enlarged in the 

 photographs. 



SYNOPSIS OF THE GENUS DASYLLIS (ASILID^). 



By Nathan Banks, Museum Comp. Zoology, Cambridge, Mass. 



The species of Dasyllis are among the largest and most promi- 

 nent of our Asilidse. In appearance they resemble bumble bees; 

 in the north where there are red-haired species of Bombus there 

 are also red-haired species of Dasyllis. Their habits and manner 

 of flight are, however, very different from that of the bumble 

 bees, and they cannot be considered as true mimics of Bombus, 

 but rather as members of a Miillerian association. Our species 

 are fairly abundant and several undescribed, although I find by 

 the collection in the Museum of Comparative Zoology that Loew 

 had manuscript names for most of the forms. The species are 

 more numerous in the east, but there are a number in the west 

 coast region, few however in the Rocky Mountain region. The 

 genus is North American, a few occurring in Central America; 

 it is an offshoot of the holarctic genus Laphria. 



Synopsis of Species. 



1. Mystax gray; head, thorax, tip of abdomen, and legs with gray 



hair cinerea Back. 



Mystax largely black, at least many black hairs above 2. 



Mystax largely yellow ; the black hairs, if any, mostly below 6. 



2. Thorax all black haired semitecta Coq. 



Thorax with pale hair above 3. 



3. Hair in front of the halters and the wings black 4. 



Hair in front of the halters and the wings yellow 5. 



4. Front and mid legs with yellow hair ; no yellow hair on abdomen, 



affinis Macq. 

 Front legs black haired; yellow hair on abdomen macquarti n. sp. 



5. Front and mid legs with much yellow hair; yellow hair on abdomen, 



sacrator Walk. 



