164 SUBAQUEOUS LIFE 



with the naked eye there can be traced hi the perfect 

 insect the cruel features and crawling legs of its former 

 state. The larvae of all dragon-flies (Odonata) are 

 distinguished by a peculiar apparatus covering the 

 mouth like a mask. They are sluggish creatures, 

 crawling on mud or weeds, and slowly swimming, 

 depending on their dingy coloration to enable them 

 to lie in wait for passing insects. Some of them have 

 the power of making a pounce forward by the sudden 

 ejection of a jet of water from their tails, but most of 

 them rely on stealth and the mask for making captures. 

 This mask can be shot out swiftly like a jointed arm, 

 bearing a formidable prehensile weapon, armed with a 

 pair of sharp pincers or toothed jaws. Woe to the 

 luckless Chironomus or ephemerid that comes within 

 reach of this terrible trap ! There could hardly be a 

 greater contrast between two stages of the same life as 

 exists between the skulking, inactive larva of repulsive 

 aspect, and the darting, soaring, glittering dragon-fly. 

 Yet both are equally voracious; the perfect insect 

 generally will be found to have his mouth stuffed with 

 small flies caught in hawking. 



Most aquatic larvae have hideous forms and forbidding 

 features. Take, for instance, one of the commonest 

 and most rapacious the Dytiscus, one of the water- 

 beetles. Seizing its prey with a pair of sharp, curved 

 mandibles, the blood of the victim flows down grooves 

 on the inner sides of these, and trickles into the 

 corners of the mouth, after which the Dytiscus some- 

 times devours the solid portion of the carcase. The 



