THE CASE MOTHS (PSYCHID^E}. 209 



in walking they oppose no resistance to the progress 

 of the caterpillar, which they would do were they 

 attached in the opposite direction, or without method. 

 Cases of considerable size are armed with large pieces 

 of leaf in similar fashion. It will be observed that these 

 twigs, or leaves, as the case may be, are arranged some- 

 what systematically, the base of those nearest the narrow 

 extremity lying beneath those nearer the wider aperture, 

 or mouth, showing the latter to have been added subse- 

 quently, proving, in fact, that the case is gradually 

 manufactured in the direction of its mouth. Through 

 this the larva habitually puts its head. It is thus easy 

 enough for it to extend its dwelling n this direction 

 while resident within it, though it necessarily exposes 

 itself to a considerable extent in applying the twigs 

 or leaves to the outside. 



The leather-like case of Animula herrichii is of 

 remarkable construction, in that the external surface is 

 destitute of any extraneous matters. 



As a larva grows, needing more accommodation, it 

 splits the habitation at the sides, weaving into the open- 

 ing portions of the vegetable substances selected, and 

 adding to the exterior fresh pieces of stick, straw, or 

 leaves, as it requires. So with Saunders' Case Moth, 

 when any accident happens to the nest, the caterpillar, 

 with incredible expedition, repairs the damage received, 

 employing the same silky stuff to fill up the hole ; and 



