VIII THE DISGUISES OF INSECTS 197 



They lay generally across leaves and twigs, as if they had 

 accidentally fallen there from some dry branch overhead ; 

 and so impossible is it to detect them by the eye that I used 

 to make it a practice, when walking along in the forests, 

 to touch every suspicious bit of dead stick I saw loose on 

 the foliage, as the only means of finding out w^hether they 

 were real sticks or Stick-insects. Sometimes they are 

 exactly the colour of lichen-covered branches, and are 

 covered with little foliaceous expansions. One that in- 

 habits the swampy forests of Borneo has these of a beauti- 

 ful olive-green colour, so as exactly to resemble a creeping 

 moss or jungermannia; and the Dyak who brought it me 

 assured me it was very curious, for he had never before 

 seen an insect grown all over with moss while alive ! I 

 was quite as much astonished as he was, for I could hardly 

 believe my eyes, and it was only after close and repeated 

 examination that I could convince myself it was not a real 

 plant that covered the animal. This insect loses all its 

 beauty when dried, and it has been very poorly figured by 

 the Dutch naturalists, and very inappropriately named 

 Ceroxylus laceratus, from its torn and shaggy appearance 

 in the preserved specimens. 



In the deserts of Egypt are some curious Mantid^e which 

 are so exactly the colour of the soil they live upon that 

 the closest inspection can scarcely detect them. It is 

 even stated that where the soil changes from brown to 

 white or yellow in a few yards' distance, the insects change 

 also, and ahvays correspond in colour to their habitation. 

 The caterpillar of a European moth, Bryophila algce, is 

 said to change in a similar manner, being yellow when 

 found on the yellow Ziche7i junij)erinus, but grey when on 

 the grey Lichen saxatilis. In this case, however, the food 

 may probably produce the change of colour, as it is known 

 to do in some other larva?. Some cases more to the point 

 have been observed by the late Mr. T. W. Wood. He 

 states that the chrysalis of the common Tortoise-shell 

 butterfly is of a very different colour according to its 

 position. When attached to a nettle, it is of a golden 

 colour ; when on a wall or fence, mottled grey ; and when 

 on a tarred paling, nearly black. Once he placed some 



