PIABITATIONS OF INSECTS. 295 



mining into the very crenatures between the two surfaces of the leaf, 

 which, being joined together at the edge, there form one seam of the case, 

 and from their dentated figure give it a very singular appearance, not 

 unlike that of some fishes which have fins upon their backs. The opposite 

 side they are necessarily forced to cut and sew up ; but even in this oper- 

 ation they show an ingenuity and contrivance worthy of admiration. The 

 moths which cut out their suit from the middle of the leaf wholly detach 

 the two surfaces that compose it before they proceed to join them together ; 

 the serrated incisions made by their teeth, which, if tliey do not cut as 

 fast, in this respect are more effective than any scissors, interlacing each 

 other so as to support the separated portions until they are properly joined. 

 But it is obvious that this process cannot be followed by those moths 

 which cut out their house from the edge of a leaf. If these were to 

 detach the inner side before they had joined the two pieces together, the 

 builder as well as his dwelling would inevitably fall. They therefore, 

 before making any incision, prudently run (as a sempstress would call it) 

 loosely together in distant points the two membranes on that side. Then 

 putting out their heads they cut the intermediate portions, carefully avoid- 

 ing the larger nerves of the leaf; afterwards they sew up the detached 

 sides more closely, and only intersect the nerves when their labor is com- 

 pleted.^ The habitation made by a moth which lives upon a species of 

 Astragalus is in like manner formed of the epidermis of the leaves ; but 

 in this several corrugated pieces project over each other, so as to resemble 

 the furbelows once in fashion.^ 



Other larvae construct their habitations wholly of silk. Of this descrip- 

 tion is that of a moth, whose abode, except as to the materials which 

 compose it, is formed on the same general plan as that just described, and 

 the larva in like manner feeds only on the parenchyma of the leaf. In 

 the beginning of spring, if you examine the leaves of your pear trees, 

 you will scarcely fail to meet with some beset on the under surface with 

 several perpendicular downy russet-colored projections, about a quarter of 

 an inch high, and not much thicker than a pin, of a cylindrical shape, 

 with a protuberance at the base, and altogether resembling at first sight so 

 many spines growing out of the leaf. You would never suspect that 

 these could be the habitations of insects ; yet that they are is certain. 

 Detach one of them, and give it a gentle squeeze, and you will see emerge 

 from the lower end a minute caterpillar, with a yellowish body and black 

 head. Examine the place from which you have removed it, and you will 

 perceive a round excavation in the cuticle and parenchyma of the leaf, 

 the size of the end of the tube by which it was concealed. This excava- 

 tion is the work of the above-mentioned caterpillar, which obtains its food 

 by moving its little tent from one pai't of the leaf to the other, and eating 

 away the space immediately under it. It touches no other part ; and 

 when these insects abound, as they often do to the great injury of pear 

 trees^, you will perceive every leaf bristled with them, and covered with 

 little withered specks, the vestiges of their former meals. The case in 

 which the caterpillar resides, and which is quite essential to its existence, 

 is composed of silk spun from its mouth almost as soon as it is excluded 



I Reaum. iii. 100—120. « Ibid. 146. 



' Forsyth on Fruit Trees, 4to edit. 271. 



