2l6 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



on the wing tiny Chironomid midges, and then returning to 

 a leaf, where the unfortunate prey was lacerated by the 

 long, strong, saw-like mandibles, and the blood and body 

 juices drunk. The empty, torn skin of the prey was then 

 dropped. As the males do not have the mandibles, they 

 undoubtedly have a wholly different food habit (probably 

 non-predatory), and this may account for the absence of 

 males from this feeding ground. No indications could be 

 found of mating or egg-laying. The flight is rather slow 

 and weak, a sort of timid fluttering. 



In the summers of 1900 and 1901 the flies of Bibioce^hala 

 elegantulus were seen commonly flitting about among the 

 great boulders of the Willow Park terminal moraine, where 

 the Big Thompson River cuts through it. The flies spent 

 most of their time at rest on the vertical sides of the 

 boulders from a few inches to two feet above the water's 

 surface, but always where the rock face was frequently 

 wetted by the spray of the dashing water. The flies rested 

 with legs and wings outstretched and body close to the 

 rock. The wings touched the rock face and, indeed, the 

 attitude seemed to be adapted to bring as much of the body 

 into contact with the wet smooth face of the rock as possible, 

 as if to resist, by increased friction, the tendency of the fly 

 to slide down the vertical surface. None of these flies was 

 seen feeding, mating, or egg-laying, although many hours 

 were spent in watching them. They were most numerous 

 on bright, sunshiny days ; on cloudy days the favorite rocks 

 were often entirely deserted. The flight is poor, and 

 numerous flies were caught readily in the hands. 



Life-history. — The complete life-history of no Blepharoc- 

 erid species is known. The eggs of no species are known, 

 and the larvae and pupae of but two species not North 

 American have been described, viz., Philorus ( Lifonetira) 

 brevirostris, described by Dewitz and Wierzeijski from 

 Europe, and Curifara torrentium described by Fritz Miiller 

 from Brazil. * 



The immature stages of one North American species, 

 JBlepharocera capitata, have been known since about 1881 



