50 



THE NATURE BOOK 



and so completely deceive their enemies. 

 Eventually each of these fraudulent twigs 



TWO STICK-LIKE CATERPILLARS RESTING 



ON AN ELDER TWIG. 



Natural size. 



becomes a Swallow-tail Moth {Uropteryx 

 sambucata). 



Some curious spider-like animals with 

 long legs are darting and gliding across the 

 surface of a clear pond, here, in a very 

 marvellous manner. They flash over the 

 water much more actively than most 

 insects move over the dry land, and yet 

 they never seem to get submerged. If 

 a small fly sh(nild fall, or is blown, into the 

 pond, you will see them rush upon it ; for it 

 is on such small game that they prey. When 

 seen on the water they apj-)ear to have eight 

 legs, but this is because their large antennae, 

 or feelers, look like a ])air of legs. A 

 glance at the illustration will show that 

 they have only si.x legs. This, it should 

 be remembered, is a characteristic feature 

 of insects. In their larval stages insects 

 often appear to have more than six legs, 



as in the case of caterpillars. Only the 

 three first pairs, however, are true legs ; 

 the claspers disappear as the insect reaches 

 its perfect form. These Pond-Skaters 

 have only six legs throughout their 

 development, and do not pass through 

 distinct caterpillar and chrysalis phases. 

 The young differ from the old apparently 

 only in size ; although they really possess 

 other differences with which we need not 

 now concern ourselves. Their marvellous 

 ]wwers of movement on the surface 

 film of the water are due to the fact that 

 their legs and bodies are clothed with 

 minute hairs which form a pile that re- 

 jects the water. They spend the winter 

 in the adult form, under banks and 

 amongst leaves and stones. In the spring 

 they deposit their eggs amongst the 

 water jilants. 



Finally, we may glance at two daffodil 

 yellow butterflies sailing along with 



A POND-SKATER. 



(Genis luijas). 



Magnified two diameters. 



merry flight. This time it is the Brim- 

 stone Butterfly (Gonoplcryx rhamni), 

 which, like the Tortoise-shell Butterfly, 



