LEPIDOPTERA. 



265 



organisation. They are continually spinning a silken thread, which 

 keeps them attached to the plant on which they live. If you touch 

 the leaf which supports them they immediately let themselves fall. 



" Nevertheless, they do not generally fall to the ground," says 

 Reaumur ; " there is a cord ready to support them in the air (Fig. 257), 

 and a cord which they can lengthen as they will ; this cord is 



Fig. 257. Looper 



hanging hy its 



thread. 



Fig. 258. Seen Fig. 259 -Front 

 at the side. view. 



Figs. 260 and 261. Remounting its 

 thread. 



only a very thin thread, but has nevertheless strength enough to 

 support the caterpillar (Figs. 258, 259). All that there seems to fear 

 is, that the thread may lengthen too quickly and the caterpillar fall, 

 rather than descend gently, to the ground. But what we must first 

 remark and admire is, that the caterpillar is mistress of its movements, 

 and is not obliged to descend too quickly ; it descends by stages ; it 

 stops in the air when it pleases. Generally it only descends at most 

 about one foot at a time, and sometimes only half a foot or a few 

 inches, after which it makes a pause more or less long, as it pleases." 



