58 HYMEiVOPTERA. 



to account for it; the brood, when disclosed under stones, 

 are certainly more protected from the influences of weather 

 than when reared in nests constructed in banks, and the 

 necessity for spinning a silken covering, might under such 

 circumstances, appear to be unnecessary ; but if this were 

 the case, all the broods thus situated might reasonably be 

 expected to be found unenclosed, but such was not the case ; 

 in many instances all the nymphs were enveloped in silken 

 cocoons. When it becomes a well-ascertained fact, that it is 

 the usual habit of a group to undergo their change from the 

 larva to the pupa state enclosed in cocoons, which the larvse 

 themselves spin previous to such a metamorphosis, may we 

 not reasonably infer that such larvae must be provided with 

 a secretion expressly adapted to such circumstances ? and 

 when, on the contrary, others are known as constantly to 

 change without spinning a cocoon, is it not equally to be 

 inferred, that such larvae are destitute of such secretion ? If 

 this be an allowable inference to draw, our difficulty appears 

 to increase when we attempt to account for the remarkable 

 deviation from the usual economy of Fovjnica fusca ; it is 

 quite possible, should such a secretion as I have supposed 

 each larva to be provided with, that it may be ejected pre- 

 viously to changing to the nymph state, but still, why some 

 should, and others should not spin cocoons, when appai-ently 

 placed under similar conditions, remains to be accounted for. 

 Some years ago I found a brood of F. fusca that had 

 constructed their abode in a rotten oak stump; the larvae and 

 pupae were contained in chambers excavated immediately 

 beneath the bark ; in this case the pupaa were naked. These 

 facts are, in my opinion, well worthy of record, offering, as 

 they do, additional instances of the wonderful and endless 

 variety observable in the operations of nature, and in how 

 admirable a manner we always find these opei-ations adapted 



