vi] LARVAE AND THEIR ADAPTATIONS 61 



mentioned above afford remarkable examples of 

 'protective' resemblance, for many of them show a 

 marvellous likeness to the twigs of their food-plant, 

 tubercles on the insect's body resembling closely 

 the little outgrowths of the plant's cortex. It has 

 been shown by E. B. Poulton (1892) that many cater- 

 pillars are, in their early stages, directly responsive 

 to their surroundings as regards colour. Usually 

 green when hatched, they remain green if kept among 

 leaves or young shoots of plants, while they turn red, 



a 



Fig. 17. c, Ruby Tiger Moth (PJiragmatobia fuliginosa); a, cater- 

 pillar ; b, cocoon. After Lugger, Insect Life, vol. n. 



brown, or blackish if placed among twigs of these 

 respective hues. This eifect appears to be due to 

 a direct response of the subcutaneous tissue to the 

 rays of light reflected from the surrounding objects. 

 The sensitiveness dies away as the caterpillar grows 

 older, since little or no change of hue in response to 

 a change of environment could be induced after the 

 penultimate moult. 



Among those families of the Lepidoptera which 



