vni ORIGIN AKD USES OF COLOUR IN ANIMALS 203 



known leaf-insects of Ceylon and of Java, species of Phyllium, 

 are so wonderfully coloured and veined, with leafy expansions 

 on the legs and thorax, that not one person in ten can see 

 them when resting on the food-plant close beneath their eyes. 

 Others resemble pieces of stick with all the minutiae of knots 

 and branches, formed by the insects' legs, which are stuck out 

 rigidly and unsymmetrically. I have often been unable to 

 distinguish between one of these insects and a real piece of 

 stick, till I satisfied myself by touching it and found it to be 

 alive. One species, which was brought me in Borneo, was 

 covered with delicate semitransparent green foliations, exactly 

 resembling the hepaticae which cover pieces of rotten stick in 

 the damp forests. Others resemble dead leaves in all their 

 varieties of colour and form ; and to show how perfect is the 

 protection obtained and how important it is to the possessors 

 of it, the following incident, observed by Mr. Belt in Nicaragua, 

 is most instructive. Describing the armies of foraging ants in 

 the forest which devour every insect they can catch, he says : 

 " I was much surprised with the behaviour of a green leaf- 

 like locust. This insect stood immovably among a host of ants, 

 many of which ran over its legs without ever discovering there 

 was food within their reach. So fixed was its instinctive 

 knowledge that its safety depended on its immovability, that 

 it allowed me to pick it up and replace it among the ants without 

 making a single effort to escape. This species closely resembles 

 a green leaf." 1 



Caterpillars also exhibit a considerable amount of detailed 

 resemblance to the plants on which they live. Grass -feeders 

 are striped longitudinally, while those on ordinary leaves are 

 always striped obliquely. Some very beautiful protective 

 resemblances are shown among the caterpillars figured in 

 Smith and Abbott's Lepidopterous Insects of Georgia, a work 

 published in the early part of the century, before any theories 

 of protection were started. The plates in this work are 

 most beautifully executed from drawings made by Mr. Abbott, 

 representing the insects, in every case, on the plants which 

 they frequented, and no reference is made in the descriptions 

 to the remarkable protective details which appear upon the 

 plates. "We have, first, the larva of Sphinx fuciformis feeding 

 1 The Naturalist in Nicaragua, p. 19. 



