THE COLORATION OF ANIMALS 



67 



protective efficacy is just the same. This is the case with the Pieridaj 

 (Garden Whites). 



All the caterpillars of our Sphingidae, on the other hand, which 

 live on bushes and trees, have on the sides of the seofments lio-ht 

 oblique stripes, seven in number, which are 

 disposed to the longitudinal axis of the body 

 at the same angle as the lateral veins of a 

 leaf of their food-plant have to the mid-rib. 

 It cannot of course be said that the cater- 

 pillar thereby gains the appearance of a leaf, 

 indeed, if one sees it apart from its food- 

 plant it does not look in the least like a leaf, 

 but among the leaves of a bush or tree this 

 marking secures it in a high degree from dis- 

 covery. Thus the caterpillar of the eyed hawk- 

 moth (Smevlnthus ocellatus), when it is sitting 

 among the crowded foliage of a willow, is often 

 very difficult to find, because its large green 

 body does not appear as a single green spot, but 

 is divided by ihe oblique lateral stripes into sec- 

 tions like the half of a willow leaf, so that even 

 a searching glance is led astray, there being- 

 nothing to focus attention on the animal as 

 distinguished from its surroundings (Fig. 3). 

 As a boy I often had the interesting experience 

 of overlooking a caterpillar which was sitting 

 just before me, until after a time I chanced to hit upon the exact spot 

 in the field of vision. 



In the majority of these caterpillars with oblique stripes, the 



Fig. 2. Longitudinally 

 striped caterpillar of a Saty- 

 rid. After Rosel. 



heightened 



by the fact that the 



likeness to the half of a leaf is 

 light oblique row is ac- 

 companied by a broader 

 coloured band, suggesting 

 the shade of the leaf's 

 mid-rib. The caterpillar 

 of Sphinx ligustrl has a 

 lilac band, and that of 

 SpJiinx atropo.s a blue one. 

 In both cases it is difficult to believe that such striking colours can secure 

 the animals from discovery, yet among the blending shadows of the 

 leaf-complex of their food-plant they greatly increase their re^ 

 semblance to a leaf-surface. Of the death's-head caterpillar (*^j9/?i')2a; 



F 3 



Fig. 3. Full-grown 

 Hawk-moth, Smerlnthus 

 stripe. 



caterpillar of the Eyed 

 ocellatus. sb, the subdorsal 



