HEARING INSECTS. 251 



for Agrotis and a few others a considerable depth of fine 

 earth or sand is necessary." * 



" Larvae, which in nature hibernate, must either be 

 stimulated by warmth and fresh food to feed up unnatu- 

 rally fast, or else through the winter must be exposed to 

 out-door temperature." Hibernating, hairy larvae must be 

 kept dry during winter. For such larvae as begin to eat 

 before the trees are leaved out, the leaves of evergreens 

 must be provided, pine leaves, chick weed, grasses and 

 mosses. On the other hand, Mr. W. H. Edwards has fed 

 belated larva? of Papilio cresphontes on dried leaves of 

 prickly ash, softened in water. He also fed another belated 

 lot with leaves of the hop-tree which had been gathered for 

 two years. These he soaked overnight, laid between blot- 

 ting-paper, and the larvae ate them readily. Larvae from 

 other countries may be fed in the same manner, the food- 

 plants being sent by mail. Mr. Greene describes what he 

 calls his "larvarium, viz., a very large box, say three feet 

 square and about the same in depth, filled partly with 

 mould covered with moss." The edges of the top of this 

 box must be smoothly shaved to suit the lid, which is like 

 the frame of a slate, the slate being knocked out. This is 

 then covered with gauze. In a box of this size small 

 branches may be held in bottles of water, and two or three 

 dozen larvae safely housed. If placed in a cool room, with 

 plenty of air, they will grow almost as large as if in free- 

 dom. Mr. Gibson strongly recommends that during the 

 winter all cages containing larvae be placed in front of a 

 window facing the east or northeast, so that the inmates 

 may be kept as cool as possible. 



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

 Mr. Sauborn, their wings often fail to properly expand on 



* Many larva? require earth during all their entire existence as such, 

 and very many more require it for pupation. The Noctuids, especially, 

 burrow in the eartb during the day, and the Oatocalse, as well as many 

 others, must, have clean litter in which to hide, for they feed only at 

 night, and lie concealed under bark, in crevices, and among grass- 

 roots and leaves during the day. 



