TEOUT 



very soft bodies, make for themselves cases. 

 Some of these cases are made from small sticks, 

 some from little pieces of stone or sand, and some 

 from a mixture of all of these substances. As 

 these cases resemble such small pieces of rubbish 

 as are frequently found in streams, care should 

 be taken that they do not get into the hatching 

 trays containing ova. 



Many of the water beetles, and practically all 

 of their larvae, will attack the ova ; they should 

 therefore be carefully excluded from the hatch- 

 ing trays. As there are about 114 different 

 species of beetles in the family of Dytiscidce 

 alone, my readers will appreciate my reason for 

 not attempting to enumerate them. It will be 

 a sufficient warning to state the fact that they 

 are all carnivorous, and their relative sizes is 

 the only thing which will decide whether the 

 beetle will eat the fish, or the fish the beetle. 



Very similar to beetles are some of the water- 

 bugs. They may, however, easily be distin- 

 guished from beetles, as the outer or anterior 

 wings of the bugs cross each other at their lower 

 ends, while the elytra of beetles, which much 

 resemble the horny, anterior wings of some of 

 the water-bugs, meet exactly in the middle line. 



63 



