246 M. Huber on the Habits of a Saw-fly. 



easier and easier to raise up the anterior part of its body, and 

 to stretch longer or more oblique threads, at its choice ; in 

 order to do this, it bent its body in the form of an arch above 

 the leaf, so as to make supports of all the threads which it 

 had stretched above it. The play and muscular strength of 

 its rings made of all these threads so many ladders, which 

 helped its body to advance on the cordage which it had spread ; 

 and the plaited nature of the rings of its belly, and especially 

 the large size of the last ring but one, greatly contributed to 

 the success of its efforts : the motion begins at the tail, it ad- 

 vances, the rings swell and contract successively, they quit 

 the threads to which they correspond in order to rest on other 

 more advanced threads, and the whole body travels two lines 

 in advance. The caterpillar then spreads fresh threads above 

 itself, and by the same process gains a little ground every 

 time; in short, it attains the object of its efforts, being always 

 turned on its back ; when it has reached the edge of the leaf 

 it stops. Such is its way of proceeding when naked. 



I was very curious to know how it would repair the loss of 

 its covering at an age when the size of its body differs from 

 what it was at first, and when a turn of ribbon two lines in 

 width is not sufficient for it. I had the satisfaction of seeing 

 this work done, which was worthy of some skilful tailor in a 

 desert island who might be obliged to make his own garment. 

 I will explain it in two words : the caterpillar had the tact to 

 make itself a complete covering out of a single fold, which it 

 cut to its measure, after having rolled it around itself. For 

 that purpose, after having made a deep fold in the leaf around 

 itself, it made a hole in the middle of the leaf, enlarged it by 

 degrees, and rolled this wide shred about itself, just as we 

 should draw a covering over us. The covering folded upon 

 itself forms a double envelope, which the insect converts to its 

 use in this position, by sewing it with numerous threads at 

 the two ends. 



Nature, as we see, is rich in ingenious expedients : so much 

 originality in the means, so much variety in the processes, so 

 much skill and depth in her views, what do these declare ? 

 what do they proclaim, — if not the indisputable, the infinite 

 wisdom of the Creator of all things ? 



EXPLANATION OF PLATE VI, 

 Fig. 1. The caterpillar, natural size. 

 Fig. 2. The same, magnified. 

 Fig. 3, 4. Different appearances of the rolling-up of the case before the 



caterpillar forms its threads. 

 Fig. 5, 6, 7. Various positions of the caterpillars in forming the case by 



means of their threads. 

 Fig. 8. The closed case. 



