vi DEFENCES OF INSECTS 221 



striking examples of special imitation of definite 

 objects. Many of the tropical Locustidae and Phas- 

 midae, in the colour, texture, and veining of their 

 elytra, are like green leaves ; others represent leaves 

 in various states of decay. In none the dissimulation 

 is carried to greater extent than in the wonderful 

 genus Phyllium, " the walking-leaf" (see Fig. 40). 

 Not only have the wings assumed the appearance 

 of leaves, the thorax and legs have been equally adap- 

 tive, and have become flat, expanded and leaf-like, to 

 the elimination of their ordinary forms. When the 

 insect is resting among its food-plant often the closest 

 scrutiny fails to distinguish the difference between the 

 animal and the vegetable. Many of the species of 

 Phasmidae the family to which this insect belongs, 

 the " spectres " or " praying insects " as they are 

 popularly called are known as " walking-sticks," 

 from their singular resemblance to twigs and branches. 

 Their colouring, form, rugosity, and arrangement of 

 the head and legs are all in accurate accord with the 

 appearance of dead sticks ; in a word, when " walking- 

 sticks " are seen stationary it seems scarcely credible 

 that an imposture is being played. In Brazil, and 

 elsewhere, some are no less than eight inches and. 

 even a foot long and of the thickness of one's finger. 

 They hang about shrubs in forests, and have the 

 extraordinary habit of holding out their limbs unsym- 

 metrically, the better to typify a branch with lateral 

 spray (see Fig. 41). 



In a case recorded by Dr. Wallace the trickery 

 does not end here. A "walking-stick" (Ceraxylus 

 laceratus) obtained in Borneo exactly resembles a 



