Walking-Leaves. 



349 



examination by spertnun anal\>is and is found to agree exactly with the colouring 

 matter of leaves. 



There is a strange difference in the external appearance of the two sexes. The 

 female has no wings, but her wing-covers are developed to such an extent that they 

 extend over two-thirds of the hind-body, and ha\-e a beautiful and complicated 

 system of nervures that very closely mimic the vcining of a leaf. This full develop- 

 ment is quite contrary to the rule that prevails in the family, as we have shown 

 in the case of the stick-Insects, where the wing-covers (when present) are too small 

 to co\er the wings. Now the male walking-leaf has expansive hind-wings which 

 nearly cover the hind-bod\-, but the 

 wing-covers are very small. This is 

 not the end of the peculiar conditions 

 prevailing among these Insects. It 

 must have been noticed that in nearl\- 

 all Insects the stoutest nervures are 

 situated at or near the fore-edge of 

 the ^^•ings to give strength to that 

 part which has to meet the resistance 

 of the air in flight. As there are no 

 fiight-wings in the case of the female 

 walking-leaf, Nature did not feel bound 

 to follow the rule. She was getting 

 up these wing-covers to imitate a leaf, 

 and shifted the strong nervures to the 

 hinder margin of the wing-covers, so 

 that when these lay resting on the 

 Insect's back they constitute the 

 apparent midrib of the leaf. If, in 

 our photograph, these are looked at 

 in comparison with the fore-wings of 

 other Insects, it will be seen also that 

 the outline is reversed — the straight 

 edge being behind and the rounded a Walking-Leaf Insect. 



edge in front. As a flying organ in this photograph of a ft-m.-ilo the wing-covers are separated to show 



, J. , " ^ , that there are no wings to be protected bv them. This sc.\ having 



SUCll a form must be pronounced given up the liaWt of flight has yet retained the wing-covers and de- 



, . 1 r 1 velopec! them in the direction ol increasing its hkeness to the leaves 



utterly wrong; but the female upon which it feeds. 



leaf-Insect having given up the ambition to fly, these organs have been devoted 

 to the important office of protection from enemies, and from this point of \-icw 

 the imperfection is turned into perfection. 



The walking-leaf Insects are restricted to the (^Id World, and there to the 

 tropical regions. India, Malaysia, and especialK- the islands ot the Pacific and Indian 

 Oceans from Mauritius and vSeychcUes to Fiji, provide us with examples. There 

 are several species, but their differences are not great, and are such as appeal more 

 to the classifying entomologist than to the readers for whom this work is intended. 

 In essentials the description of one species will serve for al). 



FLoto by] 



