219 NATURE STUD^. 



in part. Nymphs of may-flies, of most dragon-flies and 

 many water beetles and water bugs will live under the 

 same conditions, so that an aquarium for ordinary observa- 

 tion is easily kept, and there ought to be one of some kind 

 in ever}' school room, at least for a few weeks in the 

 spring. 



One of the most common of the caddis-fl}!- larvae builds 

 his house of bits of sticks or grass which he cuts in short 

 pieces with his jaws and la3-s crosswise, as children in the 

 country used to build cob houses. The}- are busy build- 

 ers and work almost constantly, but with very little judg- 

 ment or common sense. We supplied abundance of ma- 

 terial for one of these builders by cutting off bits from the 

 ends of matches. He worked fast, and soon had a much 

 larger house than he needed. Worse still, being made of 

 dry match-wood, he could not make it sink ; and, worst of 

 all, as the dry wood was wholly at one end, the house 

 stood persistently upright, despite his frantic efforts to tip 

 it over. He would lean far over one side and try to swim 

 downward, but his house had become a ship and still float- 

 ed right side up — or, rather, wrong side up for him. It 

 never occurred to him to gnaw off the silken threads with 

 which he had fastened his lumber together, and so let 

 some of it drift away. At night, when we left him, he 

 was wildly brandishing his six legs, but making no use 

 of the sharp jaws which would soon have set him and his 

 house right again. In the morning he la}^ dead at the 

 bottom of the aquarium, while his useless house floated 

 above him. 



Dragon-fly nymphs add greatly to the interest of an aqua- 

 rium. They differ widely in their habits. Some will 

 climb up a stick to the surface ; some bury themselves in 

 the mud, and others prefer to work themselves backward 

 in clear sand until only their e^^es are visible. All are vo- 

 racious, but they are also wonderfull}^ patient and will 



