MAY-FLIES AND THEIR NEIGHBOURS 223 



building" cases or tubes in which to protect the 

 more tender parts of their bodies from sticklebacks 

 and other enemies. As soon as they leave the 



j. 148. A caddis-worm denuded of 

 x 4 diameters 



egg the caddis-grubs commence building, the 

 different species and families each manufacturing 

 their dwelling-places in different forms and of 

 different materials. Even individuals of the same 



