THE INSECT AQUARIUM. 



29 



his head and legs for purposes of locomotion or reconnais- 

 sance. Various species of Limnophihts construct more 

 robust-looking cases of twigs of wood cut up into suitable 

 lengths, of pebbles, of the shells of Planorbis vortex and 

 marginatus, — some of these shells empty ; but very fre- 

 quently they lay hold of shells still occupied by living 

 snails, whilst another species selects portions of grass 

 stems, which are so arranged as to bristle out at every 

 point, like a little Sea-urchin. Some persons have 

 experimented with them, by taking them out of their 

 " cases " and placing them in a vessel of water containing 

 only fragments of coal, coloured glass, &c. The insect 

 soon constructs a new case which, of course, contrast with 

 those obtained from pond or stream. In the Geological 

 Museum, Jermyn Street, London, are several specimens 

 made entirely of quartz, taken from a stream whose floor 

 consisted of that mineral. The " flies " which result by 

 development from these Caddis-worms, are exceedingly 

 pretty little creatures, with very delicate gauzy wings, 

 usually of a sombre hue, but occasionally beautifully 

 iridescent. On emerging from the watery element, they 

 will probably seek the window-curtains as affording a 

 safe foot-hold until their integuments have hardened, 

 and their wings expanded. They will often hover about 

 the aquarium for the greater part of their winged exist- 

 ence, and sometimes deposit their eggs therein. 



We must not forget the Water-beetles, of which a large 

 variety may be obtained from any pond. The largest 

 British species, and the most desirable for keeping with 

 other species, is the Large Water-beetle {Hydi'opJiihis 

 picetis). Unlike most other water-beetles it is not pre- 

 datory, and can therefore be trusted in the same tank as 

 the fish. Its body is black, the breast covered by a 



