LEPIDOPTERA. 28 1 



After having worked for about a minute at one end of its tube, it 

 thinks of lengthening the other. It turns itself round in its tube with 

 such quickness, that you would imagine it could not have had time to 

 do so, and would think that its tail was formed in the same way as its 

 head, and possessed the same address in choosing and tearing out 

 the bits of wool. 



Furthermore, when the moth which is working at elongating its 

 case does not find the threads or hairs of wool to its taste within 

 reach of its head, it changes its place. Reaumur saw this insect walk- 

 ing, at some speed even, carrying with it its case. It walks on its six 

 front legs (Fig. 295). With the 

 middle and hind legs it clings to 

 the interior of its case. 



At the same time that the larva ■ 

 becomes longer it becomes stouter. 



Very soon its garment will be too Fig. 295.— Larva of a Tinea walking. 



narrow for it. Will it enlarge its 



old coat, or will it make itself a new one ? Reaumur discovered that 



it preferred to widen its old coat. 



That is what our naturalist saw when he placed larvae with blue 

 cases, for instance, upon stuff of a red colour. The bands which 

 extended in straight lines from one end of the case to the other, 

 showed the part that had been added. 



" From watching them at different times," says this admirable 

 observer, " I find that the means which they employ is precisely that 

 to which we should have had recourse in a similar case. We know of 

 no other way of widening a sheath, a case of any stuff that we find too 

 narrow, than to split it right up and to let in a piece of the proper size 

 between the parts which we have thus divided ; we should let in a 

 piece on each side if the shape of the tube seemed to require it. 

 This is also exactly what our larvse do, with an extra, and which with 

 them is a necessary, precaution, so as not to remain exposed while 

 they are working at the enlargement of their garment. Instead of two 

 pieces, which should each be as long as their case, they let in four, 

 each of which is not longer than half the length of their case ; and so 

 they never split up more than half the length of the case at the same 

 time, which has enough stuff left in it to keep it together while this 

 opening is being filled up." 



The wools of our stuffs furnish the moths not only with clothing, 

 but also with food. Their excrements are little grains, which are the 

 same colour as the wool they have eaten. 



When they are full grown, and the time approaches for their 



