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.
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