FA M . B LEPH AROC ICR I DÄi 



stones at the water's edge. The larvae and pupae of one European species, one Brazihan species and one 

 North American species, are known. The larvas of all Blepharoceridae yet known live submerged in 

 swiftly running clear streams, which practically limits their occurence to mountainous, or at least, to 

 hillv regions. Thev are found usually in groups of lesser or greater number in favorable spots, some- 

 times, as in the case of Blepharocera tenuipes, in Coy Glen, near Ithaca, X. V., forming « patches » of 

 hundreds of individuals clinging to the smooth rock bed of the stream, with from an inch to two inches 

 of water running swiftl}' over them. In Colorado and California tiie larvae of Bibiocephala and of 

 Blepharocera have been found more scattered, and usual!}' more deeply submerged; this is usually 

 caused, or at least the other condition made impossible, b}' the broken condition of the stream beds, 

 which are usually composed of separate stones of various sizes rather than of smooth bed rock. The 

 larvae (pi. i, f. 5, 6, 8 and g) are curious, flattened, slug-like creatures, legless, but enabled to cling 

 firmly to the rock by means of six ventral suckers (whose structure and mode of use are described b}' 

 Kellogg, Proc. Calif. Acad. Science, ser. 3, vol. 3, p. 2o3, ff. , igo3). When distvnbed, the larvae can hold 

 so fast to the rock that the bod}' is more readily torn in two than dislodged as a whole. Locomotion, 

 which, though slow, is freely accomplished, is in a lateral direction; the moving larva loosens the hold 

 of three suckers at a time and swings to one side the hinder half of the body thus released, the suckers 

 again attach this part of the bod}' in its new position, and the other half of the bod\- is loosened and 

 swung over, and thus a slow lateral translation of the larva takes place. 



The larvae seem to feed chiefly on diatoms, although other food is doubtless taken. The older 

 larvae of Blepharocera tenuipes (New York) almost always bear a dorsal, felt-like covering, which is com- 

 posed of a close growth of diatoms. The most abundant diatom in this group was one of the stalked 

 Gomphonema. The basis of the covering is the gelatinous mass at the base of the stalked diatoms. 

 Scattered upon and through this mass were individuals of Nitzschia, and several olher diatomaceous 

 genera. An examination of the alimentary canal of Blepharocera tenuipes larvœ always reveals scores or 

 hundreds of the siliceous tests of the diatoms. In the Colorado and California larvje of the various 

 Bi bliocephala species and oi Blepharocera jordani, the dorsal covering of diatoms is rather uncommon 

 though not infrequently to be seen. 



The larvae cannot live in stagnant or even quiet or slow running water. Indeed if. in the falling 

 of the stream, larva? get stranded in a suddenly made pool or still, quiet-water part of the stream, they 

 soon die. They must have the highly aerated, swift water of the stream's center. Thev like the lip of a 

 fall, the rocks of cascades, and the sides of a pot-hole in which the water is ever whirling and boiling. 

 They can live therefore only in clear, swittly running streams with a rapid fall, and this practical!}' limits 

 these insects to mountain regions. 



The pupa- (pi. i, f. lo and ii) are found in the same places as the larvae; that is, the larvae, when 

 ready to pupate, do little more than arrange themselves, almost always in small or large groups, with 

 heads pointing down-stream, and there make the last larval molt. Each pupa is fastened to the rocks 

 by six pads, three on each lateral margin of the ventral aspect of the abdomen ; these pads are not like 

 the suckers of the larva whose hold can be voluntarily loosened, but they permanently attach the pupa 

 to one spot. The pupa is even more extraordinarily shaped than the larva. It is strongly convex above, 

 with a dark brown or black, heavily chitinized bod} -wall, and is perfectly flat on its ventral aspect, 

 which lies smoothly against the rock. The wings and legs lie folded on the ventral aspect, which is 

 covered only by a thin colorless pupal cuticula. From the prothorax projects dorsally a pair of respira- 

 tory organs, each composed of four thin, double-walled plates, the outer plates of each set being strongly 

 chitinized, and acting as jirotecting covers for the two delicate mcmbrancjus inner ones itlic whole 

 arrangement like a two-leaved book, with board covers). 



Of absorbing interest to the observer is the course of emergence of the adult from its subnierged. 



