NORTH AMERICAN CADDIS-FLY LARV. 
FAMILY POLYCENTROPIDE. 
Haprtrat.—The larve are common insects in all swift streams 
of the region, and in many situations of standing and slow-mov- 
ing water. 
Hasits.—In the swift streams about Ithaca several genera 
live among the rocks, making nets of different form. The habits 
of these have been described by Miss Noyes, 1914. 
Several species of the genus Phylocentropus live in still or 
slowly-flowing water with sandy or muck bottoms. These larvae 
spin subterranean tubes of silk, which sometimes reach ten centi- 
meters in length. Often the tubes have one or mére branches, and . 
always they contain a bulbous swelling near the middle in which 
the larva probably rests, and in which pupation takes place. In 
natural position the tubes are beneath the ground, except about 
half an inch which projects upward into the water. 
In summer, when the water recedes, it is not uncommon to 
find the exposed muck margins of upland swamp streams broken 
by innumerable quantities of these Phylocentropus chimneys, pro- 
jecting upward into the air. 
The genus offers an interesting field for future study to ascer- 
tain how the larva lives and feeds within its tube; how it uses its 
long, needle-like labium in spinning, and what particular use is 
made of its peculiar mandibles, legs, and other characteristic 
structures. 
Foop oF THE Larva:.—The larve of the species that have been 
studied feed upon plancton organisms and small insects that be- 
come entrapped in the mesh of their tubes. 
DESCRIPTION OF THE LARVA:.—The frons extends back to the 
caudal margin of the head, completely separating the epicrania. 
The labrum is entirely chitinized. The pronotum is chitinized, 
the meso- and meta-nota are soft.* Spacing-humps, the prosternal 
horn, the lateral fringe, and external gills are absent. There is no 
chitinous shield on the dorsal surface of the last abdominal seg- 
ment. The prolegs are long, and are not fused on the median 
line to form an apparent tenth segment. 
*In an exotic subfamily all three thoracic segments are chitinized 
dorsally. 
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