82 ON THE HABITATIONS AND 



downy russet colour, about a quarter of an inch 

 above the surface of the leaf, and have greatly the 

 resemblance of spines. That they are the domiciles 

 of these minute larvae can be easily proved, for if one 

 of them is detached from the leaf and squeezed, a 

 minute caterpillar will be ejected, with a black head 

 and yellowish body. If the spot from which this 

 habitation was removed be examined, it will be found 

 to have a round excavation in the cuticle and paren- 

 chyma of the leaf, the size of the end of the tube. 

 The animal, like the Arab of the desert, has the 

 power of moving its little marquee from one place to 

 another, and thus eating away the part immediately 

 beneath it. All the little seared specks to be seen 

 on the leaves of pear trees, are the remains of their 

 destroying powers.* The tube in which the larva 

 dwells, and which is indispensable to its existence, is 

 of its own manufacture, spun from silk emitted from 

 its mouth, as soon as it emerges from the egg. When 

 the creature enlarges in size, it enlarges the dimen- 

 sions of its abode, by cutting it asunder in a longi- 

 tudinal direction, and then introduces a slip of new 

 materials. " But the most curious circumstance in 

 the history of this little Arab is the mode by which 

 it retains its tent in a perpendicular posture. This 

 it effects partly by attaching silken threads from the 

 protuberance at the base to the surrounding surface 

 of the leaf. But, being not merely a mechanician, 

 but a profound natural philosopher, well acquainted 



FORSTTH on Fruit Trees, 4to. 271. 



