COMBINATION OF MANY METHODS OF DEFENCE 271 



The same larva assumes a terrifying^ attitude (mimetic 

 of a vertebrate appearance) when disturbed 



As soon as a large larva is discovered and disturbed 

 it withdraws its head into the first body-ring, inflating 

 the margin, which is of a bright red colour. There are 

 two intensely black spots on this margin in the appro- 

 priate position for eyes, and the whole appearance is 

 that of a large flat face 

 extending to the outer 

 edge of the red margin 

 (see fig. 60). The effect 

 is an intensely exag- 

 gerated caricature of a 

 vertebrate face, which is 

 probably alarming to the 

 vertebrate enemies of the 

 caterpillar. The terrify- 

 ing effect is therefore mimetic. The movements en- 

 tirely depend on tactile impressions : when touched 

 ever so lightly a healthy larva immediately assumes 

 the terrifying attitude, and turns so as to present its 

 full face towards the enemy ; if touched on the other 

 side or on the back it instantly turns its face in the 

 appropriate direction. 



Fia. 60,— The larva of Puss Moth in its 

 terrifying attitude after being disturbed ; 

 full-fed ; natural size. 



