594 



THE NATURE BOOK 



but the unfortunate creature has not 

 calculated that a telescopic weapon is 

 carried by the foe, and in an instant the 

 larva shoots out its pincer-armed lip, and 

 grasps its unsuspecting victim. The 

 Dragon-fly larvae are most voracious 

 creatures, and not only are they a terror 

 to all the lesser fry of their aqueous world. 



harden, and the gauzy wings to expand 

 and dry, and then it flits away like a 

 li\-ing flash of light. 



Another terror to the inhabitants of 

 the pond is the Water Beetle [Dytisciis 

 marginalis), which in both the larva and 

 adult stages of its existence is carni^'orous 

 in its habits, and attacks all kinds of 

 aquatic insects, small fish, newts, 

 and tadpoles. The larvae have 

 cylindrical shaped, tapering bodies, 

 \\'\i\\. fairly long legs. Their head 

 is large and broad, and their 

 powerful jaws, or mandibles, are 

 arched, and perforated at the tips, 



A DIFFERENCE OF OPINION LEADS TO- 



but they are sorry cannibals. They can 

 get out of the way of their own enemies 

 with quite astonishing rapidity, consider- 

 ing the slow and deliberate manner in 

 which they move about under ordinary 

 conditions. When alarmed they expel the 

 water in their intestine suddenly and with 

 considerable force, which has the effect 

 of projecing them at a rapid rate to a 

 safe distance. 



The Dragon-fly undergoes what is 

 termed incomplete metamorphoses ; that 

 is to say, the larva does not change to a 

 quiescent chrysalis as does the larva of 

 a butterfly or a beetle, but gradually 

 changes to what is called a " nymph," 

 though anything more un-nymphlike in 

 appearance it would be difficult to imagine. 

 It was, indeed, a sorry and sardonic piece 

 of humour on the part of the worthy man 

 of science who gave these ungraceful, 

 -bloodthirsty creatures the beautiful old 

 Greek name nymph, for they are singu- 

 larly unlo\'ely. They resemble the lar\'ce 

 in general hal)it and appearance, sa\'e 

 that the body is longer, and has upon the 

 back the rudiments of wings. When it 

 is ready to undergo its final transforma- 

 tion, the " nymph " crawls up the stem 

 of a reed, and, resting in the sunshine, 

 allows its body to dry. The skin then 

 splits, and the perfect Dragon-fly emerges. 

 For a while it rests upon the empty 

 nymph-case, to permit its body-plates to 



A BATTLE ROYAL (DYTISCUS LARV^). 



so that they can suck the blood of their 

 victims. These Dytiscus larvae, besides 

 being armed with powerful jaws, have 

 very thick and tough skins, so that they 

 have comparatively little to fear from 

 foes of their own size. They are very 

 pugnacious creatures, and are given to 

 fighting amongst themselves, and if kept 

 in an aquarium deadly combats may be 

 witnessed, the vanquished becoming a 

 banquet for the victor. When ready to 

 change to the pupa stage of its existence, 

 the larva quits the water, and excavates 

 for itself a little cave or chamber in the 

 earth on the bank of the pond, and within 

 this safe retreat casts its skin and 

 becomes a dormant pupa. 



In due course, the Dytiscus beetle 

 emerges from the cave in which it has 

 passed through its final transformation, 

 and plunges beneath the surface of the 

 pond. Clad from head to foot in hard, 

 horny armour, and with the mouth parts 

 developed into powerful biting organs, 

 Dytiscus is more than a match for any 

 inhabitant of the pond, save a full grown 

 pike, or a duck, and accordingly he leads 



