io8 The Under-Water World 



Caddis-worms are well known to all 

 who investigate the mysteries of the 

 pond. They, the larvae of the Caddis- 

 flies, are experts in the art of house 

 construction and camouflage. The eggs 

 of Caddis-flies are laid in the water or on 

 vegetation overhanging. Once hatched, 

 the young larvae commence to construct 

 each a home for itself, a travelling house, 

 so that they are free to move about in 

 search of food and at the same time 

 have protection from the many creatures 

 lying in wait to secure such tender 

 morsels. The larva makes its protective 

 case of little bits of stick, leaves, small 

 shells, gravel or sand, etc., according 

 to the traditions of its species. The 

 foundation of the case is a silken sub- 

 stance secreted by the larva and is 

 tubular in shape ; whatever other build- 

 ing material is selected is fastened to the 

 outside of this tube. The case usually 

 tapers slightly toward the hind end, 



