THE NET-WINGED MIDGES (BLEPHAROCERID^) 

 OF NORTH AMERICA. 



BY VERNON L. KELLOGG. 



CONTENTS. 



Plates XVIII-XXII. 



Page 



I. Introduction 187 



II. Descriptions of New Species, with immature stages 189 



III. Relation of the new species to the known, with sugges- 



tions FOR A REVISION OF THE GENERA, AND ANALYTICAL 

 TABLES OF NORTH AMERICAN GeNERA AND SPECIES 1 96 



IV. Notes on the Structure of LARViE and Imagines 202 



V. Notes on the Habits of Larvae, Pup^e and Imagines 211 



VI. Suggestions for Work to be Done 220 



Literature Cited 223 



Explanation of Plates 224 



I. Introduction. 



The flies belonging to the family Blepharoceridag, or 

 net-winged midges, have long been of peculiar interest to 

 entomologists because of the small number of known 

 species and their supposed rarity, because of the wide and 

 discontinuous distribution of these known forms, because 

 of the remarkable aquatic life of larvae and pupse, and the 

 strange modification of the body in both these stages in 

 conformity with the curious habits, and because of the 

 unique pseudo-net-veining of the wings of the imagines, 

 produced by a series of folds in the wing membranes. In 

 a recent paper (Kellogg, 1900) the writer has called attention 

 to further interesting structural conditions in both larvae and 

 adults, especially the composition of the compound eyes of 

 the imagines of two sizes of ommatidia, with differences in 

 disposition of the retinal pigment, etc., resulting in a 

 certain accommodation to different intensities of light. 



There are at present to the writer's knowledge but fifteen^ 



iBezzi, in a paper describing the female oi Hapalothrix lugubris, in Zeitsch. f. Hym . 

 u. Dipt., 1901, and seen by the writer only after this paper had been sent to the printer, 

 states that eighteen species are known. 



( I ) . [ 187 J January 24, 1903. 



