MINING CATERPILLARS. 235 



and dry, and consequently these only exhibit the 

 valley without the river. (See p. 231.) 



On looking at the back of the leaf, where the wind- 

 ing line begins, we uniformly find the shell of the 

 very minute egg from which the caterpillar has been 

 hatched, and hence perceive that it digs into the leaf 

 the moment it escapes from the egg, without wan- 

 dering a hair's breadth from the spot; as if afraid 

 lest the air should visit it too roughly. The egg is, 

 for the most part, placed upon the midrib of the rose- 

 leaf, but sometimes on one of the larger nervures. 

 When once it has got within the leaf, it seems to 

 pursue no certain direction, sometimes working to 

 the centre, sometimes to the circumference, some- 

 times to the point, and sometimes to the base, and 

 even, occasionally, crossing or keeping parallel to 

 its own previous track. 



The most marvellous circumstance, however, is 

 the minuteness of its workmanship ; for though a 

 rose leaf is thinner than this paper, the insect finds 

 room to mine a tunnel to live in, and plenty of food, 

 without touching the two external membranes. Let 

 any one try with the nicest dissecting instruments to 

 separate the two plates of a rose leaf, and he will 

 find it impossible to proceed far without tearing one 

 or other. The caterpillar goes still further in mi- 

 nute nicety ; for it may be remarked, that its track 

 can only be seen on the upper, and not on the under 

 surface of the leaf, proving that it eats as it pro- 

 ceeds only half the thickness of the pulp, or that 

 portion of it which belongs to the upper membrane 

 of the leaf. 



We have found this little miner on almost every 

 sort of rose-tree, both wild and cultivated, including 

 the sweet-briar, in which the leaf being very small, 

 it requires nearly the whole parenchyma to feed one 

 caterpillar. They seem, however, to prefer the foreign 



