IO4 The Colours of Animals. 



IV. 



I. The genus Deilephila, of which we have in Eng- 

 land three species the Euphorbia Hawk-moth, 

 the Galium Hawk-moth, and the Rayed Hawk- 

 moth is also very instructive. The caterpillar of 

 the Euphorbia Hawk-moth begins life of a clear 

 green colour, without a trace of the subsequent 

 markings. After the first moult, however, it has a 

 number of black patches, a white line, and a series of 

 white dots, and has, therefore, at one bound, acquired 

 characters which in the Elephant Hawk-moth, as 

 we have seen, were only very gradually assumed. 

 In the third stage, the line has disappeared, leaving 

 the white spots. In the fourth, the caterpillars have 

 become very variable, but are generally much darker 

 than before, and have a number of white dots under 

 the spots. In the fifth stage, there is a second row 

 of white spots under the first. The caterpillars 

 not being good to eat, there is, as has been already 

 pointed out, no need for, or attempt at, concealment. 

 Now if we compare the mature caterpillars of other 

 species of the genus, we shall find that they repre- 

 sent phases in the development of the Euphorbia 

 Hawk-moth. The Sea Buckthorn Hawk-moth, 

 for instance, even when full grown, is a plain green, 

 with only a trace of the line, and corresponds, there- 



