THE MOSAIC OF COLOURS 



they hold it between their legs. Male and female, each bearing 

 tokens of its species which can be recognized at a distance — in 

 Brazil one species has splendid red wings, and the wings of another 

 larger species are golden-yellow, and rimmed with black — chase one 

 another, and finally cling together, and climb down a reed in order 

 to lay their eggs under the water. From these eggs the young dragon- 

 flies emerge in a wingless state ; they look like bits of broken reed ; 

 and they wear a mask, which enables them to creep along the 

 bottom of the pond unnoticed by their prey, and to seize it with 

 their suddenly protruded underlip, which is formed like a pair of 

 tongs. Such immature forms, which do not resemble the adult 

 insect, are known as larvae. At every moult the wings grow a little 

 longer, until the larva ascends to the surface, where its skin splits 

 open, and the dragonfly launches itself upon the air. 



There are masters of mimicry in the family of the Locustidae. 

 These insects afford a nutritious and agreeable diet for many birds, 

 mammals, reptiles and other insects ; they have therefore to reckon 

 upon very heavy losses, which cannot be made good save by the 

 most successful adaptation to the environment, and profuse multi- 

 plication. The eggs are commonly protected by burying them in 

 the ground. Such is the habit of the notorious Migratory Locusts 

 of Southern Brazil, which from time to time appear in such colossal 

 numbers that their swarms obscure the sun, and the fields are laid 

 completely bare for many miles around. In the Argentine a swarm 

 of Locusts was observed which was sixty miles in length and twelve 

 in width ! 



I never noticed the huge locusts which were so common in the 

 coastal bush of Pernambuco until they flew ofT, unfurling their 

 red hind-wings. Directly they settled these were furled, and covered 

 by the green fore-wings, so that the insect was lost in the surrounding 

 foliage. But there are in Brazil certain "Leaf-locusts," or "Leaf- 

 insects," whose mimicry of leaves is perfect in its smallest details. 

 The fore- wings of these insects are held perpendicular, so that when 

 they settle on a twig the wings represent a perpendicular leaf, and 

 the sunken head the leaf-stalk. The wing has precisely the shape 

 of a leaf, and ends in a point ; a long vein, with smaller diagonal 

 veins which run across the wing, represents the innervation of a leaf 

 (Plate 29, II, 2). One species mimics a withered leaf with its brown 

 wings ; another mimics a green leaf with brown and yellow mottlings 

 at the tip, so that a partly withered and mildewed leaf is represented 

 with amazing accuracy. In another species spots of mildew are seen 



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