228 CALIFORNIA ACADEMY OF SCIENCES [Pkoc. 4th Se*. 



on their clothes and go home. 1914, U. S. Bur. Ent., Tech. 

 Series, No. 26, p. 31. 



152. Simulium vittatum Zett. 

 Narrows, VII-1. Malloch det. 



Family BLEPHAROCERIDyE 



Fig. 12. Bibiocephala grandis O. S. 



These flies could be mistaken for Tipulidae at first glance. 

 The venation is quite characteristic and there are creases in 

 the membrane which give the impression of a secondary 

 venation. The females are predaceous. The larvae live in 

 swift streams, attaching themselves to rocks by means of 

 ventral suckers. They feed on minute aquatic organisms. 

 Many of the flies are swept away in the swift current as they 

 emerge from the pupal cases, being unable to get their wings 

 unfolded in time. This may account for the few species in 

 existence. 



These flies are not uncommon along some of the swift 

 streams of Oregon and one species of Blepharocera taken in 

 the Hood River valley, as well as a small species of Bibio- 

 cephala occasionally collected, will be described later by Mr. 

 Leroy Childs. These two undescribed species were not found 

 in any such numbers as were the two forms listed below. 



