202 Proceedings of the Biological Society of Washington. 



Michigan; and Missouri. Two specimens from Washington, D. C, were 

 bred from larvae preying on Aphis euonymi. 



Syrphus ribesii vittafrons new variety. 



When he described S. rectus, Osten Sacken mentioned four specimens, 

 two males and two females, which had a distinct brown median stripe on 

 the face. No locality was given, but in the vicinity of Washington speci- 

 mens with this peculiarity appear to be much more numerous than typical 

 ribesii, and it is therefore thought best to designate this form by a dis- 

 tinctive varietal name. Besides having the facial stripe the pile on the 

 thorax is more deeply golden. 



Type, male, Maryland near Plummers Id., Md., April 17, 1913 (W. V. 

 Warner); allotype, Cabin John, Md., September 13 (F. Knab) ; para- 

 types, vicinity of Washington, D. C, for records of which see p. 183. 



Type : Cat. No. 20286, U. S. N. M. 



The National Collection contains specimens of typical ribesii from New 

 Brunswick, Connecticut, Colorado, Washington (State), Alaska, Cali- 

 fornia, and Mexico. Specimens from Alaska are inclined to have longer 

 and much thicker pile on the body. 



Brachyopa flavescens Shannon. 



This species was described from males. (Insec. Insci. Mens. 3, 1915, 

 p. 144. ) The female may be recognized from those of other North Ameri- 

 can Brachyopa, except notata, by its reddish yellow frons and thorax and 

 from notata by its nearly bare arista, narrower frons and less elongate 

 scutellum. 



Key to the Species of Brachypalpus (sensus strictu). 



1. Abdomen without crossbands 2. 



Abdomen with crossbands 3. 



2. Posterior margin of fourth abdominal segment yellow, first two 



joints of fore tarsi and first three joints of middle and hind 



tarsi orange colored inarmatus Hunter. 



Abdomen unicolorous; the first joint of the front and middle 

 tarsi yellowish, the following joints and all of the hind tarsi 

 dark frontosus Lw. 



3. Third antennal joint large and blackish; pile on frons. Legs 



entirely black rileyi Will. 



Third antennal joint rather small, somewhat reddish; no pile 



on frons. Legs for the most part reddish brown . . parvus Will. 



B. INARMATUS Huuter. 



Eyes in male narrowly separated. Antennae reddish brown, arista 

 lighter. Tips of tibiae and extreme tips of femora yellow; first two 

 joints of fore tarsi yellow, the other black; first three joints of middle 

 and hind tarsi yellow, the others black. Hind tibiae of male un- 

 armed. Thorax brassy with a purplish reflection and with short yellow 



