FAMILIES ORPHNEPHILIDjG, BLEPHARO- 

 CERID/E AND RHYPHID^ 



These three families are not especially well represented in 

 the fauna of the United States and comparatively little need be 

 said about two of them. 



The Orphnephilidae are small brownish or yellowish flies 

 without bristles or hairs. We have only one described species in 

 this country, viz, Orphnephila testacea Ruthe, common to Europe 

 and North America. Nothing is known about the transforma- 

 tions of any member of this family. 



The Blepharoceridae, however, are insects of much greater 

 interest and especially on account of their curious larvae and on 

 account of an unusual arrangement of the viens in the wings 

 which has been pointed out in the table of families. The adult 

 flies look somewhat like mosquitoes but do not bite. The eyes 

 are divided, the upper half containing large ocelli and the lower 

 half small ones. The larvae are very peculiar looking objects, 

 having appparently but seven segments and being furnished 

 with conical leg-like structures on most of the segments. On the 

 under side of the body is a row of circular suckers by which they 

 attach themselves to rocks in swift running streams. Each of 

 the suckers is surrounded by a little fringe of tracheal gills or 

 there are tufts of such gills near the sides of the body. The pupa 

 is formed within the last larval skin but subsequently the skin is 

 cast so as to leave the pupa naked. The pupa also clings to the 

 rocks, the skin of the back being hard and making a sort of scale 

 over the body. On the underside, however, it is delicate and 

 soft and furnished with six suckers by which it clings to the rocks 

 so firmly that they can hardly be removed without breaking 

 them. Comstock has watched the flies issue from the pupa skins. 

 The pupae occur in groups so as to form black patches on the 

 rocks. Each one rests with its head down the stream. The fly 

 emerges through a split in the skin between the thorax and 



124 



