October 1891.] 



PSYCHE. 



157 



grains were walking oft* in a mass. 

 This protecting portico disappears 

 during pupation. 



A larva, which in some years is 

 quite abundant, spins for itself a case 

 of black silk, weighted with vegetable 

 matter. It is about 15 mm. long, 

 terete, tapering to the rear end, where 

 there is a small hole. The cases of the 

 young are quadrangular at the anterior 

 end, which end during pupa- 

 tion is closed with a thick disk, § (©) 

 having in its centre a thinner cir- 

 cular area perforated with holes- 

 In the illustration (fig. iS) 

 the adult case is represented too small. 

 This species does not bear confinement 

 well, and I have never reared it. 



Hydroptilidae. I have been dis- 

 appointed at finding only one species of 

 Hydroptilidae in my brook, and this I 

 have not reared. The case (fig. 19) 

 is flat, gray and seed-like, and is 

 attached bv its edge to the stones Fig. 19. 

 in the brook, where the current is rapid. 



Hydropsychidae. The most in- 

 teresting species of the order found 

 in Stony Brook, and also abundant in 

 various smaller brooks, weaves for itself 

 a little net, probably for the purpose of 

 catching its food. This species, with its 

 nets, has been found to be very com- 

 mon in other parts of the United States. 

 The net (fig. 20) is up- 

 right, supported by a 

 small vertical arch or 

 ring of vegetable bits,^^^C 

 and the opening of the Fig-. 20. 



larval house is always on the up-stream 

 side of the net. In some places the 

 nets and their accompanying houses 

 are found singly on the bottom, or on 







the stones in the brook — in other places 

 they are thickly clustered together, or, 

 placed side by side, they may extend 

 nearly across the brook. 



The larvae are gray, with an arcuate 

 body, and tufted gills hanging thickly 

 from the under side. They pupate in 

 May. The nets disappear during pupa- 

 tion, and the houses, which, while the 

 larvae were active, were shiftless ar- 

 rangements of loose vegetable bits, or 

 grains of sand carelessly held togethei 

 with silk, are now (fig. 

 21) oblong domes, 

 strongly constructed of 

 little stones, and fastened 

 at their edges to the 

 rocks, pebbles or sticks in the brook. 

 The whole is lined with silk, small 

 openings being left at each end for the 

 respiratory current. These larvae die 

 almost immediately when transferred 

 from the rapidly flowing streams which 

 they affect, to the tranquil waters of an 

 aquarium. But like many other sensi- 

 tive species, the well-developed pupae 

 can be make to emerge in a set-basin, 

 which has a constant stream of water 

 from the faucet flowing through it. 



Another species of this family, be- 

 longing to the 

 genus Plectroc- 

 nemia, makes a 

 tube of mud 

 (fig. 22) which 

 I at first thought 

 must be manu- 

 factured by 

 some large 

 worm. I saw 

 the ends of 

 these tubes projecting from the muddy 



Fig. 32. 



