TRICHOPTERA 567 



at Ithaca, N. Y., made cases in the form of cm-ved cornucopias (Fig. 

 697, b); those found in Wisconsin by Vorhies, who first described 

 the species, make a case with decided lateral flanges and a hood that 

 completely covers the head of the larva. 



Mystdcides sepulchrdlis. — The larva of this species and its case 

 were described by Lloyd. It was found in ponds and in slow deep 

 pools of creeks; it lives among the rubbish on the bottom. The case 

 (Fig. 697, c) consists of a slightly tapering tube of sand or of minute 

 fragments of bark, lined with silk; it measures about 12 mm. in 

 length. On opposite sides are fastened pine needles, or grass stems, 

 or slender sticks, which extend beyond both ends of the case. Before 

 pupation a sheet of silk with a minute perforation in the center is 

 spun across each end of the case. 



Tricenddes. — The larvae of species of this genus live in ponds and 

 bays of creeks among branches of submerged plants. They are able 

 to swim rapidly from place to place through the open water. The case 

 (Fig. 697, d) is made of thread-like fragments of leaves arranged in a 

 spiral. It resembles in form the case of Phryganea (Fig. 695, &), but is 

 much smaller and more flexible, and the leaf -fragments are much 

 narrower. 



Family ODONTOCERID^ 



The immature stages of only a single species belonging to this small 

 family have been described in this country; the following notes re- 

 garding this species are from Lloyd ('21). 



Psilotreta frontalis. — The larvae were found in up- 

 land streams and were confined to the riffles and the 

 portions of the streams with stony bottoms. The case 

 of the mature larva (Fig. 698) is a slightly curved 

 cylinder made of sand; cases of immature larvae differ 

 only in being tapered toward the caudal end. The 

 case of the pupa has a fiat pebble set neatly within 

 the aperture at each end. All spaces around these 

 stones are tightly closed with heavy silk, leaving no 

 apertures for the circulation of water; this is an unusual 

 feature in the case-building Trichoptera. 



During their early life the larv^ are free-moving, 

 crawling separately over the bottom of the stream. But 

 in the early spring, just before pupation, the larvae Fig. 698. — 

 develop a remarkable gregarious habit. Almost all of C a s e o f 

 the larvffi within certain areas of the stream congregate Psilotreta 

 on the sides of a few selected stones in such numbers (After 

 that their cases are sometimes piled one on top of another Lloyd.) 

 to the depth of an inch or more, while other stones in the region are 

 entirely uninhabited. The cases are always placed parallel to each 

 other, with their cephalic ends directed toward the surface of the water. 



Family CALAMOCERATID^ 



This is a small family of which only one American larva is known. 

 The habits of this species have been described by Lloyd, from whose 

 accounts I quote. 



