POND LIFE 



671 



catches them at a certain angle, it is 

 practically impossible to detect these 

 threads, so that unless one is thorouglily 

 acquainted with the habits and methods 

 of the spider, one is rather apt to look upon 

 its hurrying from one stem to another as 

 a somewhat useless waste of energy, and 

 an altogether profitless performance. In 

 a little while, how- 

 ever, when the weav- 

 ing operations have 

 been more or less satis- 

 factorily completed, 

 the spider commences 

 fresh tactics ; it pays 

 a succession of visits 

 to the surface of the 

 water, and each time 

 it descends takes with 

 it a large supply of 

 air - bubbles. If we 

 now watch the spider 

 carefuUy, we shall see 

 that at each descent 

 it makes straight for 

 the spot amongst the 

 stems of the water- 

 weeds, where it has 

 been so busy, and 

 proceeds with the aid 

 of its wonderful comb- 

 like claws to comb 

 out from the body- 

 hairs the entangled 

 air-bubbles. This per- 

 formance is repeated 

 again and again, until 

 the little dome of 

 the "nest" becomes 

 clearly visible, as 

 though composed of 

 burnished silver — an 

 effect produced by the imprisoned air 

 which the spider has brought down from 

 the surface and thus stored away. The 

 Water Spider, hke aU her species, is armed 

 with powerful, hollow jaws with a fine 

 opening at their point, through which 

 she sucks the juices of her prey, and 

 many a soft-bodied water larva falls a 

 victim to her guile. 



Mimicry plays an important part in the 

 lives of many pond insects. For instance, 

 a common object that is to be seen float- 

 ing on the surface of almost every pond, 

 and which at the first glance appears to 



WATER "STICK" 

 SKATER 



be a slender piece of stick, is the Pond- 

 Skater {Ranatra). If we cautiously drop 

 a small stone into the water, the little 

 piece of stick suddenly becomes animated, 

 and darts away, skimming over the 

 surface of the water at a rapid rate. 

 Looking closer, we see that what we 

 at first mistook for a piece of stick is 



really an insect, and 

 that attached to the 

 lx)dy are six very thin, 

 fairly long legs. This 

 Pond-Skater, or Pond 

 " Stick" insect, as it 

 is sometimes caUcd, 

 lives at the surface of 

 the pond, and moves 

 about w i t h great 

 rapidity by means of 

 its delicate slender 

 legs. It is in many 

 respects a remarkable 

 insect, and its move- 

 ments are well worth 

 closely watching. A 

 few minutes' careful 

 observation will re- 

 veal the fact that one 

 of the insect's popular 

 names, at least, is a 

 very apt one, for it 

 will be seen that the 

 insect does not swim 

 through the water, but 

 actuall}' skates along 

 the surface without 

 breaking the delicate 

 surface film. When 

 we come to consitler 

 how extremely atten- 

 uated are the limbs 

 of the Pond-Skater, 

 we at once realise how impossible it 

 would l)e for the insect to tra\cl with 

 such swift, darting movements if it had 

 to propel itself through the water. 



Another good example of insect mimicry 

 — though one that it is not quite so easy 

 to find as the Pond-Skater — is the so- 

 called Water Scorpion {Ncpa cincrca), 

 which when resting amongst the brown 

 leaves at the bottom of a shallow pool 

 looks just like part of a withered willow- 

 leaf. The insect is about an inch in 

 length, and has a somewhat eUii)tical 

 shaped body terminating in a pair of 



INSECT OR 



(RANATRA). 



POND- 



