THE PINE PROCESSIONARY 121 



needle to the twig, from the twig to the branch, from the 

 branch to the bough and from the bough, by a no less 

 angular path, to go back home. It is useless to rely 

 upon sight as a guide on this long and erratic journey. 

 The Processionary, it is true, has five ocular specks on 

 either side of his head, but they are so infinitesimal, so 

 difficult to make out through the magnifying-glass, that 

 we cannot attribute to them any great power of vision. 

 Besides, what good would those short-sighted lenses be 

 in the absence of light, in black darkness? 



It is equally useless to think of the sense of smell. 

 Has the Processional any olfactory powers or has he 

 not? I do not know. Without giving a positive answer 

 to the question, I can at least declare that his sense of 

 smell is exceedingly dull and in no way suited to help 

 him find his way. This is proved, in my experiments, 

 by a number of hungry caterpillars, that, after a long 

 fast, pass close beside a pine-branch without betraying 

 any eagerness or showing a sign of stopping. It is the 

 sense of touch that tells them where they are. So long 

 as their lips do not chance to light upon the pasture-land, 

 not one of them settles there, though he be ravenous. 

 They do not hasten to food which they have scented from 

 afar; they stop at a branch which they encounter on their 

 way. 



Apart from sight and smell, what remains to guide 

 them in returning to their nest? The ribbon spun on 

 the road. In the Cretan labyrinth, Theseus would have 

 been lost but for the clue of thread with which Ariadne 

 supplied him. The spreading maze of the pine-needles 



