86 ON THE HABITATIONS AND 



tirely of silk, and similar in its general plan of 

 construction to that last described, except in point 

 of the material with which it is composed, and, like 

 it, feeds on the parenchyma of the leaf alone. Pear- 

 trees are much infested with these minute larvae ; 

 and, in spring, they frequently beset the whole under 

 side of the leaves with their abodes; these are of a 

 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 larvfe 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, so soon as it emerges from the egg. 

 When the creature enlarges in size, it increases the 



' Forsyth on Fruit-Treet, 4to. 271. 



