THE INSECT AQUARIUM. 



27 



like "a living flash of light" after the less powerful butter- 

 fly, and seizing it in its fore legs, nip off the wings and 

 devour the tender body. In their aquatic or larval con- 

 dition, they are equally ravenous. They wander over 

 the mud of the bottom, often covering their bodies with 

 that substance, in order that they may more easily 

 approach their prey without observation. Their usual 

 mode of progression is very remarkable. The insect 

 obtains its supply of oxygen by drawing in a quantity 

 of water through an opening or valve in the last segment 

 of its body. This water 

 is brought into contact 

 with the respiratory ap- 

 paratus, by which the 

 oxygen is extracted, 

 and, should the insect 

 wish to move forward, 

 the valve is opened and 

 the water ejected in a 

 powerful jet. The whole 

 force reacts upon the 

 insect with the result of 

 propelling it forward. 

 Should it desire to capture another insect, or a very 

 small fish, it lies quietly in wait, perhaps buried, except 

 the head, in the mud. A movement of the body 

 might betray it, but it waits until its prey is near, 

 and then its head seems suddenly to leave the body, 

 dart after the unsuspecting victim, and seize it in the 

 terrible jaws. As a matter of fact, it is literally " two- 

 faced." We often hear deceitful people spoken of as 

 being " two-faced," but only in a metaphorical sense. 

 Here we have the reality, and the two faces are used 



Fig. 12. 

 Dragon-fly. 



