NATURE'S CRAFTSMEN 



LARVAL CAIRNS OR DOMICILES OF NET-MAKING CADDIS WORM 



pea to that of a pea-nut. Some lie upon the bottom in 

 separate masses; most are attached to small stones of 

 various sizes. Some of the pebbles are flat, and cover 

 the others like a roof; indeed, one or more pieces of 

 goodly size, leaned up one against the other, may usu- 

 ally be found in every group. All are so arranged as 

 to form a rude sort of den or hut. In fact, they are the 

 larval homes of the net-making caddis worm — an insect 

 which belongs to the same order as the case-making 

 caddis (Trichoptera), but to a different family (Hy- 

 dropsy chidse). 



Let us pull apart one of these stone domiciles. Here 

 within the den, and commonly within a small tube, or 

 a cavity, sometimes sparsely, sometimes thickly silk- 



274 



