enemies rather than otherwise, possibly because nature expended the 

 energy and force necessary to produce them in providing a large 

 supply of ova, nature never expending force in useless directions. 

 Psyche, of course, is somewhat analagous, until we reach the point 

 that it lays its eggs in the case and can reproduce itself partheno- 

 genetically. In Hybernia, Cheimatobia &c., the matter is different and 

 probably the female is apterous for greater facility in hiding. When 

 the leaves are off the trees, insectivorous birds have an immense ad- 

 vantage, and they have also to search in the winter much more keenly 

 for a supply of food. The males are protected by their resemblances 

 to dead leaves &c., the females with their large bodies could not thus 

 readily protect themselves (compare the sexes of A. cescularia in nature). 

 At the same time they produce very many eggs and the use of almost 

 all energy in this direction may have some effect. These females are 

 also active walkers etc., and can get into crannies and so on, quite the 

 reverse to those of Orgyia and Psyche. The two classes in fact, appear 

 to have nothing in common in this direction. Before leaving this 

 subject, it would, perhaps, be well to mention the case of Buton 

 hirtaria, a species closely allied to the apterous genera Nyssia and 

 Phigalia. This is a species the female of which has much the habits 

 of the apterous species, crawling over the trunks of trees, rarely flying, 

 and laying its eggs in crannies &c. There is frequently a tendency 

 to partial atrophy in this sex, and its connection with the apterous 

 condition of its allies has been mentioned by more than one writer. 

 Possibly I should not leave the females of Psyche without some further 

 reference to their wonderful power of parthenogenetic reproduction, 

 but a full account of parthenogenesis would evidently be out of place 

 here. 



Geddes and Thomson say, referring to the essential difference be- 

 tween the male and female Coccus : " This is not a mere curiosity of 

 the entomologist, but in reality a vivid emblem of what is an average 

 truth throughout the world of animals the preponderating passivity 

 of the females, the predominant activity of the males ; " and again he 

 writes : " Throughout the class of insects there are numerous illustra- 

 tions of the excellence of the males over the females, alike in muscular 

 power and sensory acuteness. The diverse series of efforts by which 

 the males of so many different animals, from Cicadas to birds, sustain 

 the love-chorus, affords another set of illustrations of pre-eminent 

 masculine activity." The females of Psyche reach among insects the 

 extreme development of passivity. As larvte, pupas and moths the 

 females never leave the cases which serve as a protection during the 

 larval and pupal stages and as a nidus for the ova of the imago. 



(4). SIZE. In close connection with the consideration of apterous 

 and semiapterous females, is that of size. We have before noticed 

 that some species lay but few eggs, and take great care of them, whilst 

 others lay large numbers and leave them largely to chance. In the first 

 group we find the females differing little in size from the males, and 

 in some genera Acronycta, Orrhodia &c., there is little even in the 

 relative sizes of the abdomina to tell which specimens are males and 

 which females ; but among those species which lay a large quantity 

 of eggs, we find some whose females fly actively, whilst others are 



