NORTH AMERICAN CADDIS-FLY LARVZ. 
it makes its case fast with a cement of silk. Here it is protected 
against the ravages of prowling enemies and against the greater 
danger of suspended silt. 
Those larvee which transform in the earth of the stream’s bot- 
tom, enter the soil where it is firm and hard; submergence in silt 
would mean their destruction. When entering the soil the larva 
stands on its head, with its case perpendicular to the bottom, and 
slowly enters, dragging its-case with it. I do not know by what 
method digging is accomplished. 
Foop or THE Larvai.—The larve eat vegetable matter of 
almost every kind. In the laboratory they show little preference 
between dead or living plants, terrestrial or aquatic. Under nat- 
ural conditions, as shown by examinations of stomachs of larve 
taken in the streams, both dead leaves and fresh aquatic plants, 
when the latter are to be had, are consumed. 
Prriop OF EMERGING.—The imagoes first appear early in May 
and continue to emerge until late June. In emerging, the pupz 
swim to the surface of the water, transform, and take flight with- 
out climbing onto any support. Their cast pupal skins are often 
common objects along the margins of upland streams. 
DESCRIPTION OF THE LAaRvA.—Length, 30—35 mm.; breadth, 
4.5—5 mm. 
The Head.—Straw-yellow marked with dark-brown as fol- 
lows: A mark starting at the base of each mandible extends di- 
agonally back along the outer edge of the frons to the hind margin 
of the head, almost touching the epicranial suture; a mark begins 
behind and slightly below each eye and extends to the hind margin 
of the head, almost paratteling the upper mark; a white area sur- 
rounds each eye. The under side of the head is slightly cloudy, 
but does not have the well-developed smoky stripe of N. stygipes. 
The mandibles are dark-brown, except for a triangular spot on 
the outer surface, which is lighter. The labrum and the sclerites 
of the lower mouth parts are straw-colored, narrowly bordered 
with brown. 
The Thorax.—The prothorax is straw-yellow, marked with 
dark-brown ; the pattern of the dorsal surface is shown in figure 9g. 
The epimeron is dark-brown, narrowly bordered with black; the 
ventral side of the prothorax is white, with a triangular black 
chitinous piece behind the “horn.” 
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