SOME AQUATIC INSECTS 75 



old husk from which it has escaped, until the 

 body has grown to its full length and the wings 

 have expanded and hardened. The late Alfred 

 Lord Tennyson has left a very beautiful and 

 accurate description of this final transformation 

 in the following lines : 



" To-day I saw a dragon-fly 

 Come from the wells where he did lie. 

 An inner impulse rent the veil 

 Of his old husk : from head to tail 

 Came out clear plates of sapphire mail. 

 He dried his wings : like gauze they grew ; 

 Thro' crofts and pastures wet with dew 

 A living flash of light he flew." 



Of far more sombre appearance is the common 

 Dytiscus Water Beetle (Dytiscus marginalis), 

 another ferocious insect inhabitant of ponds and 

 sluggish streams. It is in many ways an interest- 

 ing and remarkable insect, leading a very active 

 life in both the larval and adult stages of its 

 existence, and undergoing a complete metamor- 

 phosis. In March and April, the female Dytiscus 

 begins the work of depositing her eggs, making 

 by means of her ovipositor an incision in the 

 stems of the rushes below the surface of the 

 water, and depositing a single egg in each 

 incision. About three weeks later the larvae 

 begin to emerge, and if there is a plentiful 

 supply of food, grow very rapidly, casting their 

 skins from time to time, and attaining their full 

 growth in about five weeks from the time of 

 hatching out of the egg. They then quit the 

 water, and digging a chamber in the earth on 

 the bank of the pool, change to pupae. In the 



