16 PROCEEDINGS OF THE NATIONAL MUSEUM, vou. 60. 



BIBIO XANTHOPUS Wiedemann. 



Bib. lio] xantJwpus Wiedemann (C. R. W.), Ausz., zweifl. Ins., vol. 1, 1828, 

 p. 80 [New York]. 



KEY TO SUBSPECIES OF XANTHOPUS. 



A. Pleura of female wholly dark ; male with the hair more copious and longer, 



usually darker, sometimes black B. xanthopus palliatus. 



AA. Pleura of female often in part yellow to rufous; male with less abundant 



and shorter hair usually pale on thorax and abdomen B. xanthopus 



xanthopus. 

 BIBIO XANTHOPUS XANTHOPUS Wiedemann. 



Bibliographical reference as for species. 



Male. — Head, body, and coxae black, head with black, body and 

 coxae with usually pale yellow to grayish hair; femora and succeed- 

 ing leg joints yellow to rufous, dark-tipped, the very unequal spurs 

 of front tibiae rufous ; humeral ridge, narrowly pale ; wings slightly 

 fumose, a little deeper costally, all of the veins dark, the anterior 

 ones and stigma darkest. 



Female. — The female differs by having shorter, pale hair on head, 

 the coxae and pleura often in part yellow to rufous, pale humeral 

 ridge more distinct, and wings more yellowish, sometimes dusky 

 fumose. 



Length of wing, 5.5-9.5 mm. 



The range of this subspecies, on the basis of specimens examined, 

 extends from Maine, Ontario, and Michigan to Pennsylvania, Ten- 

 nessee, Colorado, and New Mexico. It has been reported also from 

 Quebec. 



BIBIO XANTHOPUS PALLIATUS new Bubspscies. 



Differs from the typical subspecies in darker colors, more abundant 

 pubescence, and somewhat greater average size. The pleura of 

 female usually are wholly dark ; the male has more abundant, longer, 

 and darker hair, sometimes wholly black. This subspecies bears 

 somewhat the same relation to the eastern race of xanthopus that 

 hirtus does to alhipennis. Length of wing, 7.5-9.5 mm. 



Type. — A male, Moscow, Idaho, May 7, 1894; allotype, female 

 mounted on same pin with type. Paratypes from Tacoma and 

 Seattle, Washington, British Columbia and Vancouver Islands 

 (Aldrich). 



SPECIES NOT IDENTIFIED. 

 BIBIO ARTICULATUS S»y. 



Bibio articulatus Say (Thomas), Journ. Acad. Nat. Scl. Philadelphia, vol. 



3, 1823, p. 78; Compl. Writings, vol. 2, 1859, p. 69 [Pennsylvania]. 



Since there is no type specimen of Say's species and the original 



description does not refer to the length of tarsal joints, this species 



became unidentifiable when Lowe described dbhrevmtus with short 



hind metatarsi. 



