CH. III.] INSECTS WHICH FORM COCOONS. 65 



and uneven, it is smooth and finely polished, and, 

 moreover, instead of being formed in the earth it is 

 built upon leaves, so that the caterpillar is under the 

 necessity of fetching its materials from a consider- 

 able distance. 



Reaumur found these caterpillars upon the oak 

 and apple, and some of them formed their cocoons 

 during the night, without his having observed the 

 process. He noticed, however, that the earthen 

 walls of the cocoon were moistened, although the 

 earth at the bottom of his breeding-cage was quite 

 dry. It was evident, therefore, that the caterpillar 

 had moistened the earth, but he could not imagine 

 how a caterpillar, which, in constructing its cocoon, 

 is for the most part enclosed within, could give to 

 the exterior so smooth and polished a surface ; and 

 had he not been more of a naturalist than a gour- 

 mand, his curiosity in this respect would not have 

 been satisfied ; for, having observed one "morning 

 that his only remaining caterpillar was making prep- 

 arations for forming its cocoon, by attaching a few 

 silken threads as a base upon a leaf, he quitted his 

 study at two o'clock to dine, and returning in less 

 than an hour to watch its manoeuvres, he found that 

 it had, during his short absence, completed three 

 quarters of its cocoon, the mode of construction of 

 which was found to be somewhat similar to that 

 employed by cottagers in building mud walls, the 

 chopped straw which is employed to bind the mud 

 together being replaced by the meshes of a loose 

 silken web of an oval shape. When this web is 

 nearly completed, the insect collects a quantity of 

 earth within the net merely sufficient for its future 

 purposes. It then shuts itself up in this net by en- 

 tirely closing the aperture, and commences the 

 building of its mud walls by moistening one of the 

 bits of earth with a liquid which it emits from its 

 mouth ; when well moistened, it pushes the paste 

 through the meshes of its nei, when it immediately 

 G2 



