62 BRITISH BUTTERFLIES. 



noteworthy that it is just then that the size of the caterpillar becomes 

 materially enlarged. He says : " At the end of its second stage, the 

 little caterpillar is no more than two or three times as long as at birth, 

 while the rate of growth, subsequent to that, is so great that, in its 

 mature condition, it is ordinarily twenty or more times as long as at 

 birth, and its bulk increases in a far greater ratio. The change of 

 colour and markings has, therefore, direct relations with its visibility, 

 and it is, in this later period, even more than in the earlier, that we 

 see how completely colours which are protective have established 

 themselves. It is now that these oblique streaks upon the sides of the 

 body are apt to show themselves, which, as Lubbock has pointed out, 

 diverge from the general line of the body at much the same angle as 

 the veins of a leaf part from the midrib. Often the colour of these 

 streaks is graduated into the ground-colour in a manner which closely 

 resembles the shadows of a raised vein upon a leaf, and it is only 

 when we examine such objects in free nature that we see how perfect 

 the deception becomes." 



The coloration of butterfly larvae opens up a wide field for study, 

 and the exposed life the larvae often lead, renders them subject to the 

 attacks of various enemies. The colour of the larva is often an 

 important factor in its preservation, and this operates in two very 

 different ways. In one group of larvae the colours are such as to 

 respond either in general appearance or in detailed arrangement (or 

 both) with the place chosen by the larva for the purpose of rest ; in 

 the other group of larvae the colours are conspicuous and suggest 

 danger to a foe. The first class of larvae are sometimes said to have 

 a "cryptic," the latter a "warning," coloration. One of the most 

 striking instances of allied larvae presenting the two different kinds of 

 coloration is exhibited by the larva of Vapilio machaon, which, 

 feeding on fennel, and probably offensive to the taste, presents bright 

 " warning colours " of green ringed with black, whilst that of 

 Iphiclides podalirius, feeding on rosaceous plants, and assumedly 

 palatable, is of a green colour, delicately marked laterally with pale, 

 and, assuming all the appearance of a leaf of its foodplant, forms one 

 of the best examples known to us of " cryptic " coloration in a 

 comparatively large butterfly larva. But this cryptic coloration is again 

 twofold in its form ; there is the coloration, as in that of Iphiclides 

 podalirius, in which the larva bears by colour and position an exact 

 and detailed resemblance (in this case a sloe or plum leaf) to some 

 particular object, and there is another in which the general appearance 

 of the larva, combined with the details of its surroundings, presents a 

 general harmony with the environment that not only prevents the 

 larva from being conspicuous, as it would if removed from its setting, 

 but also makes it agree with such remarkable fidelity with the various 

 items that go to make up its surroundings, that it is practically 

 undiscoverable. The case of Characces jasim (antea, pp. 55-56) will 

 recur at once fco the mind, and should here be referred to. 



Scudder observes (op. cit., p. 859) that "the colours of caterpillars 

 are by no means so various, nor the patterns so complicated, as is the 

 case with the winged butterflies themselves, but it is nevertheless true 

 that, as a general rule, the different species may be separated from one 

 another with considerable certainty by their marking and colours alone. 

 With caterpillars, the variety of the dermal appendages goes far 



