no ROD AND RIVER 



The food of the caddis is generally of a vegetable 

 nature, though there are one or two species which 

 live partly, if not entirely, on animal food. When 

 the larva has lived for its full period, and is about 

 to change into the pupal condition, it closes the 

 aperture of its case with a very strong net, having 

 rather large meshes, and lies securely therein 

 until it is about to change into the winged state. 

 It then bites its way through the net with a pair 

 of strong mandibles, comes to the surface of the 

 water, breaks from its pupal envelope, and shortly 

 takes to flight. The larger species ascend up the 

 stems of aquatic plants before leaving the pupal 

 skin, but the smaller merely stand on the cast 

 skin, which floats raft-like on the water. 



1 There are one or two species whose cases are 

 not movable, but are fixed to the spot whereon 

 they were made. In order, therefore, to com- 

 pensate for the immobility of the case, the larva 

 has a much larger range of movement. In the 

 ordinary species, the creature holds itself to the 

 extremity of the case by means of hooks at the 

 end of its body, which can grasp with some force, 

 as anyone knows who has pulled a caddis larva 

 out of its house. But when the case is fixed, the 

 abdominal claspers of the larva are attached to a 

 pair of long foot-stalks, so that the creature can 

 extend its body to some distance from the entrance 

 of the tube.' 



