294 



CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



occasionally in low growing shrubbery at the very edge of 

 dense forests. 



595. Ceria tridens Loew 

 Pendleton, VI 1 1- 18 (Black, Thompson). 



Family CONOPIDjE 



Fig. 30. Dahnannia pacifica Banks. 



These are flower flies and are not usually very conspic- 

 uous. Some of the species resemble slender wasps while 

 others are more thick-set. The term "thick headed flies" is 

 sometimes applied to them, this being no reflection on their 

 mentality. Not much is known of the early stages but cer- 

 tain species have been bred from adult Hymenoptera, and, 

 according to Dr. Williston, from Orthoptera. The flies 

 evidently deposit their eggs on the bodies of some bees in 

 flight and have been observed several times attempting to 

 do this. 



596. Physocephala affinis (Will.) 



Hood River, VII-7 to IX-4, and La Grande, IX-20 

 (Cole); Vale, VIII-15. 



597. Physocephala burgessi (Will.) 

 Big Lake, VII-20 (Bridwell). 



