LEPIDOPTERA. 207 



teen legs. The first three pairs of legs are covered with a shelly 

 skin, are jointed, and tapering, and are armed at the end with a 

 little claw, the other legs are thick and fleshy, without joints, but 

 elastic or contractile, and are generally surrounded at the ex- 

 tremity by numerous minute hooks. There are six very small 

 eyes on each side of the head, two short antennae, and strong jaws 

 or nippers, placed at the sides of the mouth, so as to open and 

 shut sidewise. In the middle of the lower lip is a little conical 

 tube, from which the insects spin the silken threads that are used 

 by them in making their nests and their cocoons, and in various 

 other purposes of their dconomy. Two long and slender bags, 

 in the interior of their bodies, and ending in the spinning tube, 

 contain the matter of the silk. This is a sticky fluid, and it flows 

 from the spinner in a fine stream, which hardens into a thread so 

 soon as it comes to the air. Some caterpillars make but very 

 little silk ; others, such as the silk-worm and the apple-tree' cater- 

 pillar, produce it in great abundance. 



Some caterpillars herd together in great numbers, and pass the 

 early period of their existence in society ; and of these there are 

 species which unite in their labors, and construct tents serving as 

 a common habitation in which they live, or to which they retire 

 occasionally for shelter. Others pass their lives in solitude, 

 either exposed to the light and air, or sheltered in leaves folded 

 over their bodies, or form for themselves silken sheaths, which 

 are either fixed or portable. Some make their abodes in the 

 stems of plants, or mine in the pulpy substance of leaves ; and 

 others conceal themselves in the ground, from which they issue 

 only when in search of food. 



Caterpillars usually change their skins about four times before 

 they come to their growth. • At length they leave off eating en- 

 tirely, and prepare for their first transformation. Most of them, 

 at this period, spin around their bodies a sort of shroud or co- 

 coon, into which some interweave the hairs of their own bodies, 

 and some employ, in the same way, leaves, bits of wood, or even 

 grains of earth. Other caterpillars suspend themselves, in various 

 ways, by silken threads, without enclosing their bodies in co- 

 coons ; and again, there are others which merely enter the earth 

 to undergo their transformations. 



