216 THE COLOURATION OF INSECTS 



The general colouration was a mottled stony grey. After 

 the first moult the lighter parts of the markings became 

 chalky white, and as the caterpillars always lay close 

 together in a mass, and fed on the flat surface of the 

 leaf from the upper parenchyma only, the resemblance 

 to a bird dropping was very close. At the next moult 

 the caterpillars became darker, and as they grew larger, 

 after the third moult, were of a rich brown. They now 

 had different habits, feeding from the edge of the leaf 

 in the manner of all large caterpillars, and no longer 

 massing together. 



When full grown they were extraordinarily procryptic, 

 being of the same rich brown as the leaf stalks, with green- 

 ish and purpUsh mottlings, the body being swollen here 

 and there with numerous scale-like excrescences accurately 

 resembling scales at the bases of the leaf stalks, and 

 rugosities of the bark. The caudal horn, projecting 

 forward over the back, also helped in this likeness. The 

 caterpillars now rested along twigs and leaf stalks, and 

 adopted a special attitude, which rendered them more 

 procryptic. 



An instance has been given of the use of an aposeme 

 on certain occasions only. The following is a very re- 

 markable instance of a structure useful at one stage of 

 development being apparently made use of to protect 

 a subsequent stage. 



The larva of the Lasiocampid moth, Chrysopsyche varia, 

 is quite conspicuous, being coloured a rich chestnut brown 

 with large pale blue spots. When full grown it has in 

 addition on the dorsum of each segment from 4-10 

 a dense patch of very short, closely set fine hairs of 

 glistening white. 



It has been already mentioned as showing peculiar 

 limitations of instinct (p. 200). When full fed, it spins a 

 firm brown cocoon of the type usual among Lasiocampidae. 

 The point of interest is that at one end of the cocoon, 



