Vol. XI] COLE AND LOTETT—LIST OF OREGON DIPT ERA 247 



274. Bombylius major Linn. 



Common at Hood River and Corvallis and probably in 

 many other parts of Oregon. Corvallis, 1II-4 to IV-24. 

 Latest date at Hood River, V-28 (Cole). 



275. Bombylius silvus Cole 



Parkdale, VI-8 (Cole). 1919, Proc. Cal. Acad. Sci. Ser., 

 4, IX, p. 225. 



276. Heterostylum robustum O. S. 

 Lewisburg, VII-5 (Black). 



277. Anastoechus barbatus O. S. 



Hermiston, IX- 18 (Rockwood). This form has in the 

 past been made a synonym of nitidulus Fabr., the European 

 species, but Cresson has recently compared European speci- 

 mens with ours and believes it best to keep Osten Sacken's 

 name. 1919, Proc. Acad. Nat. Sci. Phila., LXXI, p. 179. 



278. Systoechus oreas O. S. 



Common at Hood River and Forest Grove in June and 

 July. 



279. Ploas amabilis O. S. 



Burns, V-19 (Thompson). A single specimen. This 

 species undoubtedly occurs in eastern Oregon in large num- 

 bers as it is common in parts of arid, eastern Washington. 



280. Ploas atratula Loew 

 Common at Hood River, V-10 to VI-22 (Cole) . 



281. Ploas fenestrata O. S. 



Hood River, V-8 to VI-22 (Cole); Burns, V (Thomp- 

 son). 



282. Ploas melanocerata (Bigot) 



Hood River, VI-2 to VI-26 and Mosier, VI-14 (Cole and 

 Childs). 



