246 FEESH-WATEB, AQUAKIA. 



ciently to use its legs, and when it is attacked by an enemy 

 it withdraws itseK deeply into its tube. Most of these laiTse 

 may be considered herbivorous, though at times they are 

 not unwilling to partake of a carnivorous diet. They will 

 occasionally eat a portion of a worm, pieces of beef or mutton, 

 sometimes very young fish. A few of the Caddis-wonns are 

 thought to be entirely carnivorous, feeding as a rule upon other 

 aquatic larvae. However, it is well to take for granted that 

 the Caddis-worms which are suitable for the aquarium are 

 herbivorous. These little creatures should not be placed in a 

 tank in which choice weeds are growing, or they wlU certainly 

 do a great deal of harm ; and the best way to keep these very 

 interesting insects is to place them in small aquaria, where 

 they may be easily seen at their work, and in which small 

 quantities of weeds may be put as required. Caddis-worms 

 shotdd not be kept together in great numbers, or they will 

 interfere with one another. They will live for a long time in 

 the aquarium, often apparently without eating anything at 

 aU. When they do not feed, the period at which they will 

 enter the pupal state is considerably postponed. Caddis- 

 worms of various species may be found at almost any season 

 of the year. 



As the time arrives at which it is necessary for the larva 

 to enter the pupal-hood, it in most oases makes preparation 

 for that change by fastening its tube to a stone or water- 

 plant, and covering the open ends of it with a kind of silken 

 net, so constructed as to keep out all enemies, and let ia the 

 water necessary for respiration. Sometimes this grating is 

 made with the help of pieces of stone or vegetable matter. 

 Occasionally a larva closes up one end of its case in the 

 manner just described, and with the head protruding at the 

 other end digs a hole in the bottom of the stream, in which 

 it almost half buries its tube vertically. When it has done this 

 it is supposed to change its position ia the case before it 

 becomes a pupa. Very recently I saw a Caddis-worm in an 

 aquarium performing this act of semi-interment. I removed 

 it to another vessel, and it soon reburied itself. A few days 

 after the larva has closed up its case, it enters the pupal 



