314 The Caddis-Worm and, its Houses. 



happened. The best way is to let each caddis have a small 

 jar of river water for itself, and which should contain the sub- 

 stance it is wished its house should be built of. The water 

 should be changed daily, so as to let the caddis have always a 

 fresh supply of oxygen, and also to keep the materials bright 

 and clean which it employs. 



When the period arrives for these larvas to become pupas 

 they gradually lose their activity, until at last they withdraw 

 their head and legs entirely into their cases, and remain in a 

 completely dormant state for a short time until their last trans- 

 formation, when they burst open their cases, and rise to the 

 surface of the water in their "new and glorious forms of perfect 

 flies. They dry their wings and skim along the surface of the 

 water, their instinct leading them to perform their new career 

 as if they had been accustomed to that state of existence all 

 their lives. 



The period in which the transformation from larvas into 

 flies takes place does not always fall at the same time at 

 different parts of the country. In the south of England it 

 generally occurs about the middle of May. 



The colour of the fly is brown. It is possessed of four 

 wings, which are equally long, and very much resemble net- 

 work. Whilst at rest the wings are placed longitudinally. 

 It has also long antenna). The flies always keep near the water. 

 Their great enemies in all states of their existence are irout, 

 with other fish, who devour them freely ; the trout even eat 

 a and all of the caddis ; although they greatly prefer 

 tlicni without the Btonea and sticks which cover the bodies, 

 as then they consider them exceedingly dainty morsels, and 

 in that condition they are thus found a killing bait by the 

 angler. 



But caddis-worms are equally as rapacious as the trout 

 themselves. They hare really a tremendous appetite, taking 

 into consideration their si/.e. I have observed thai if this was 

 not satisfied they were never sufficiently nourished In l>e able 

 to nndergo their final transformation, but would die whilst 

 existing in the pupa siai". When 1 kept these creatures I 

 used t<> feed them on pieces of uncooked meat, which they would 

 eagerly seize from my fingers, ami ravenously devour. It used 



to surprise nie to sec how much such small animals could 



manage to get through ata meal. They will also eat a common 

 house-fly, the wings, legs, and head being alone rejected as 



unlit. But meat, if that he cooked, no caddis will offer to 

 touch, however hungry he may he. It is only whilst the 



oad i • in the larva Btate thai they are so carnivorous. 



When living in the Streams their food consists of the numerous 

 creatures that exist there, as insects, polyps, mollusks, and 



