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HABITS OF L,ARVAK 



The larvae of all species are aquatic, living in swift-running 

 streams, and particularly in those that have rocky bottoms — to which 

 they attach themselves by means of the suckers on the ventral surface 

 of their bodies. 



The food consists of diatoms, algae, and other small aquatic or- 

 ganisms. 



HABITS OF IMAGINES 



The imagines are never found except in the vicinity of streams 

 suitable for their larvae. The females are predaceous, feeding upon 

 small insects such as chironomid midges; the males are recorded as 

 feeding on nectar. 



Owing to the fact that the larvae require very rapidly flowing pure 

 water as their habitat no species are likely to be found except in moun- 

 tainous regions, and it is improbable that any occur in Illinois. 



BiBiocEPHALA sp. ? 



Larva (PI. XL, Fig. i). — Length, 9-10 mm. Pale brown on dor- 

 sum, yellowish white on venter ; head and chitinized dorsal thorns 

 black. 



Antennae elongate, constricted portions of joints whitish, the re- 

 mainder black; entire dorsum of head chitinized, black; mouth-parts 

 pale. Thoracic segments without thorns ; a black triangular chitinized 

 area on dorsum proximad of the first abdominal armature. Last 

 segment of complex and all the abdominal segments except the apical 

 with 4 stout horn-like protuberances on middle of dorsum, a much 

 longer one near each lateral margin, and a pair of them on lateral 

 margin, the upper one, with a shoulder at its middle, directed outward 

 and armed at apex with 2 long hairs, the lower one directed slightly 

 downward ; apical segment with a pair of protuberances on dorsum 

 and a number of long hairs on margin of apex of venter. Ventral 

 suckers of moderate size. Lateral ventral blood-gills 5 in number in 

 each group ; apical blood-gills stout, 4 in number. 



Pupa (PI. XL, Figs. 2, 4). — Length, 6.5-8 mm. Dark brown. 



Thoracic respiratory organs consisting of the usual 4 upright 

 plates (Fig. 6), the length of the outer one being about 1J/2 times as 

 great as its greatest width. Dorsal surface covered with minute, slight- 

 ly raised dots ; each abdominal segment with a group of larger black- 

 ish dots on each side about midway from median line to lateral 

 margin, and between this group and the lateral margin a slight eleva- 



