204 DARWINISM chap. 



on a plant with linear grass-like leaves and small blue flowers ; 

 and we find the insect of the same green as the leaves, striped 

 longitudinally in accordance with the linear leaves, and with 

 the head blue corresponding both in size and colour with the 

 flowers. Another species (Sphinx tersa) is represented feeding 

 on a plant with small red flowers situated in the axils of the 

 leaves ; and the larva has a row of seven red spots, unequal 

 in size, and corresponding very closely with the colour and 

 size of the flowers. Two other figures of sphinx larvse are 

 very curious. That of Sphinx pampinatrix feeds on a wild 

 vine (Vitis indivisa), having green tendrils, and in this species 

 the curved horn on the tail is green, and closely imitates in 

 its curve the tip of the tendril. But in another species 

 (Sphinx cranta), which feeds on the fox -grape (Vitis vulpina), 

 the horn is very long and red, corresponding with the long red- 

 tipped tendrils of the plant. Both these larvae are green with 

 oblique stripes, to harmonise with the veined leaves of the 

 vines ; but a figure is also given of the last-named species after 

 it has done feeding, when it is of a decided brown colour and 

 has entirely lost its horn. This is because it then descends to 

 the ground to bury itself, and the green colour and red 

 horn would be conspicuous and dangerous ; it therefore loses 

 both at the last moult. Such a change of colour occurs in 

 many species of caterpillars. Sometimes the change is seasonal ; 

 and, in those which hibernate with us, the colour of some 

 species, which is brownish in autumn in adaptation to the 

 fading foliage, becomes green in spring to harmonise with the 

 newly -opened leaves at that season. 1 



Some of the most curious examples of minute imitation 

 are afforded by the caterpillars of the geometer moths, which 

 are always brown or reddish, and resemble in form little 

 twigs of the plant on which they feed. They have the habit, 

 when at rest, of standing out obliquely from the branch, to 

 which they hold on by their hind pair of prolegs or claspers, 

 and remain motionless for hours. Speaking of these pro- 

 tective resemblances Mr. Jenner Weir says : " After being 

 thirty years an entomologist I was deceived myself, and took 

 out my pruning scissors to cut from a plum tree a spur which 

 I thought I had overlooked. This turned out to be the larva 

 1 R. Meldola, in Proc. Zool. Soc, 1873, p. 155. 



