Vol. XI] COLE AND LOVETT—LIST OF OREGON DIPTERA 281 



492. Melanostoma coerulescens Will. 

 Mary's Peak; Mt. Jefferson (Lovett). 



493. Melanostoma dubium Zett. 

 Rock Creek, 111-30; Duffy's Prairie, VII-26 (Lovett). 

 Doubtfully assigned here. 



494. Melanostoma mellinum (Linn.) 

 Common in the Willamette and Hood River Valleys. 



495. Melanostoma obscurum (Say) 

 Mary's Peak, VIII (Lovett). 



496. Melanostoma stegnum (Say) 

 Common, V to VIII. 



497. Leucozona lucorum (Linn.) 

 Mary's Peak, VIII (Lovett). 



498. Eupeodes volucris O. S. 

 Common, V to VIII. 



499. Didea fasciata Macq. 

 Common, VII to VIII, at altitude of 3,000 to 6,000 feet. 



500. Didea laxa O. S. 

 Common, IV to VIII. Found at low altitudes during 

 early summer and late fall, but most common at altitudes of 

 2,500 to 6,000 feet in forests near clearings, hovering in 

 shafts of sunlight that strike down through little open 

 glades. 



501. Didea pacifica Lovett 

 Parkdale, VII-12 (Cole). 1919, Proc. Cal. Acad. Sci., 

 Ser. 4, IX, p. 246. 



502. Lasiophthicus pyrastri (Linn.) 

 Common. 



503. Lasiophthicus pyrastri unicolor Curtis 

 In the early summer of 1914, the vetch aphis, Macro si- 



