LEPIDOPTERA. 243 



etc., be provided for such Noctuid larvae as naturally lie con- 

 cealed, such as Orthosia, Xanthia, Noctua, etc., "while for 

 Agrotis and a few others a considerable depth of fine earth or 

 sand is necessary." 



"LarviB, which in nature hibernate, must either be stimulated 

 l)y warmth and fresh food to feed up unnaturally fast, or else 

 through the winter must be exposed to out-door temperature." 

 For such larvtB as begin to eat before the trees are leaved 

 out, the leaves of evergreens must be provided, pine leaves, 

 chickweed, grasses and mosses. Hibernating, living larviXi, 

 must during the winter be kept dry, otherwise the damp seems 

 to hang about their fur, and causes them to be attacked by a 

 white fungus ; while smooth larvae require the natural damp- 

 ness of the soil. Mr. Gibson strongly recommends that during 

 the winter all cages containing larvae be placed in front of a 

 window facing the east or north-east, so that the inmates may 

 be kept as cool as possible. 



When the moth is fairly out of the pupa, as remarked by Mr. 

 Sanborn, their wings often fail to properly expand, on account 

 of the want of moisture, "the insect being unable to expand its 

 wings in a heated, dry room. He has avoided this difficulty 

 by placing the insect just emerged, or about to come forth, 

 beneath a bell-glass, within which he had placed moistened 

 pieces of bibulous paper." 



Mr. Trouvelot has noticed that the difference in size of the 

 wings of moths or butterflies is due to the fact that some of 

 the fluid thrown into the wings during their development 

 escapes from a break in the surface of the wing, so that this 

 wing is smaller than the other. He has, by pinching a wing- 

 while thus developiug, caused the fluid to "flow from the punc- 

 ture, and immediately the wing so wounded ceased to grow, 

 while the three others continued their development to its full 

 extent." "I have sometimes advanced the development of the 

 wings of Telea Polyphemus. I selected for this purpose, 

 pupae very far advanced in their transformation, as is shown by 

 the looseness of the pupal skin, and by the color of the wings 

 of the moth, which can be seen through it. I took carefully 

 the pupal skin from around the moth and suspended the insect 

 in the position that Lepidoptera take when emerging from the . 



