LEPTOCERIDE. 
DESCRIPTION OF THE CasE.—The case of the mature larva, 
figure 165, has the form of a slightly-curved cylinder of sand 
grains. Immature larve cases differ only in being tapered 
toward the caudal end. 
The case of the pupa has a flat pebble set neatly within the 
aperture at each end of the tube. All spaces around these stones 
are tightly closed with heavy silk, leaving no respiratory aper- 
tures. The habit of enclosing the pupa tightly, without provision 
for respiratory currents, is unusual among case-building Trichop- 
terous larve, but is always practiced by the cocoon-making family, 
Rhyacophilide. 
FAMILY LEPTOCERIDé:. 
Hapitat.—The known Leptocerid larve of the American 
fauna are inhabitants of standing waters—lakes, ponds, and the 
dilatations of streams—except Leptocerus ancylus, which is found 
on stones in the riffles of streams, as well as on the stones of wave- 
beaten lake shores. 
Though the most abundant of our Trichoptera belong to this 
family, the early stages of but few have been described, and the 
habits of these few are but imperfectly known. At times, during 
the early days of July, the black iron bridge across the northern 
end of Cayuga Lake appears as white as snow, with millions of 
adult insects of this family, mostly the beautiful snowy species of 
the genus Leptocella. At such times a passing train sends a cloud 
of countless numbers of the insects into the air, after a few min- 
utes’ flight to settle again as a white covering upon the bridge. 
Hasits.—The habits of so few species of our fauna are known 
that it does not seem advisable to generalize on the activities of 
the entire family. Those that are known will be described under 
the various species. 
DEscRIPTION OF THE Larvai.—Distinctive characters. A 
suture beginning in the region of the eye dips downward and ex- 
tends back to the hind margin of the head. The femur of the hind 
legs, and in most species of the middle legs, is divided into two 
segments. 
The Head.—The head is oval, with long antennz arising close 
behind the mandibles. The labrum is much broader than long, 
95 
