148 KANSAS UNIVERSITY SCIENCE BULLETIN. 



portion of the anterior costa, where fifteen or more — the num- 

 ber being- variable — long, stiff hairs project cephalad, curving 

 upward {S3-S). The hind wings are very weak and delicate, 

 and these hairs are of use in coordinating the movements of 

 the hind wing with those of the fore wing, resembling some- 

 what the "hamulus" of the Hymenoptera. 



The anterior margin of the costa is only slightly roughened 

 —covered with low, knob-like processes, distad of the hairs— 

 the basal two-thirds of its length, but from here on as far as 

 the beginning of the clavus these knobs become lengthened out 

 into spine-like scales pointing distad. The margin of the 

 clavus is comparatively smooth except where roughened at the 

 humeral angle. 



The membranes of this wing are transparent and thin, and 

 were often separated from each other to form a sac, when 

 boiled too long in caustic potash. This is in harmony with the 

 studies of Weismann, Kiinkel d'Herculais, Dewitz, Van Rees 

 and Pratt, which established the fact that insect wings are of 

 hypodermal origin, being evaginations of the integument, and 

 the separation of these membranes through the action of 

 caustic potash shows plainly that the wing membrane is made 

 up of two laminae, an upper and a lower, which are fused to 

 one another between the veins. The veins, except the costa, 

 are almost without chitinization, and the subcosta could be 

 made out only when it was filled with air as in newly emerged 

 specimens. 



The fore wing is quite flat, except the clavus, which is bent 

 somewhat ventrad, and that portion of the clavus between the 

 anal vein and the costa is bent quite sharply ventrad, so that 

 it is almost horizontal in position when the wings are folded 

 along the side of the body. When the insect is at rest and the 

 wings are in this position the anal angles of the fore wings fit 

 up closely against the edges of the scutellum of the meso- 

 thorax, and their edges are contiguous from the distal end of 

 the clavus to the tip of the wing. Through the gap between 

 the claval portions of the wings can be seen the posterior mar- 

 gins of the hind wings, which are contiguous throughout the 

 claval region, their anal angles fitting against the small oval 

 sclerite of the metathorax (the second tergal sclerite). 



