Protective Resemblance 



6^7 



under-surface, but in South Africa the wings are 

 spread out, showing the brownish-grey upper side 

 which harmonises with the colours of the rocks in that 

 region (189). A well-known instance of perfect protec- 

 tive resemblance is afforded by the Indian leaf-butterfly 

 {Kallima itiachis). Its wings above are conspicuously 

 adorned with purple and yellow, but beneath they 

 are grey or brown, closely resembling a dead leaf. 

 As the insect rests on a twig with wings folded over 

 its back, the head and feelers are hidden beneath the 

 fore-wings whose apex is produced into a point. 

 From this a dark line like the mid-rib of a leaf runs 

 across the wings, terminating at the pointed " tail " 

 of the hind-wing which rests in contact with the twig, 

 simulating a leaf-stalk. Likeness to leaves is to be 

 noted in other insects. Among the Orthoptera the 

 Tree-grasshoppers (Phasgonuridae) often have their 

 fore-wings of an oval shape, a green colour, and with 

 the neuration closely resembling that of a leaf; while 

 the "Leaf-insects" among the Phasmidse not only 

 have their wings like leaves but the segments of their 

 legs flattened out to form leaf-like expansions. 



Other Phasmids with their very long, thin and 

 wingless bodies and slender legs are transformed into 

 " walking-sticks." Likeness to twigs is also strikingly 

 shown by the "looper" caterpillars of moths of the 

 family Geometridae. These caterpillars have lost all 

 their abdominal pro-legs, except the two hindmost 

 pairs. Clinging tightly to a branch with these they 

 stretch out their slender bodies in a rigid attitude, 

 the six thoracic legs being directed forward in close 

 contact with the under surface of the thorax and so 

 hidden from view (fig. 172). The resemblance to 

 twigs is often increased by projections or tubercles on 

 certain segments of the hind-body, while the colour is 

 usually a shade of brown or grey, often with mottled 



