NORTH AMERICAN CADDIS-FLY LARVE. 
DESCRIPTION OF THE CasE.—The case is tubular, tapering 
gradually from front to rear, and is not curved (figure 41). It 
is made of narrow, somewhat quadrangular, bits of leaves arranged 
in spiral form, wound from right to left. Different cases vary 
considerably in size, but usually they are about 5 cm. long, 5 mm. 
wide at the front, and 3 mm. wide at the hind end. The spiral 
usually has from Io to 12 turns. 
The case of the pupa is about 36 mm. long and has little or no 
taper. It is sealed at both ends with a sieve of silk. 
FAMILY LIMNOPHILID:. 
Hasitat.—Limnophilid larve are fitted for life in almost 
every aquatic situation. In pond and slow-moving streams, espe- 
cially those that dry completely during the drought of summer, 
their numbers far outnumber all other Trichoptera together. As 
the water becomes more swift the number of species becomes less, 
until in the swiftest water, in which loose stones come to rest, one 
finds only species of the genus Neophylax, but these often in great 
numbers. ‘They are absent from the brinks of falls and from the 
parts of streams where the waters rush over bare bedrock. 
Apparently in direct relation to the kind of water inhabited 
the development of gills has taken place. In those species that 
inhabit standing water the gills are large and numerous—often 
many-branched. In species of faster moving water the gill sur- 
face is noticeably less, and in Neophylax—the Limnophilid of the 
rapids—the gills are few and are reduced until hardly more than 
thread-like rudiments. 
To this family belongs the European Enoicyla, which has the 
only terrestrial larvee known to occur in the order Trichoptera. 
Larva Hasirs.—Little can be said that will cover the habits 
of all of the Limnophilid larvee. ‘The habits of each species are 
discussed separately on the following pages. 
In preparing for pupation the larve retire to some secluded 
spot where there is little danger of molestation during the quiescent 
pupal period. One species at least, Limnophilus indivisus, buries 
itself among the submerged roots of sedges; more often the larve 
hide in the crevices of sticks or stones. So far as we know, only 
the larve of Neophylax remain in the open. These larve attach 
38 
