436 Transactions. 



X. orophyla are almost identical in colour, but have very different markings. 

 Selidosema fenerata differs strikingly in both wing-outline and colour, the 

 forewings of the male being pale yellowish-brown, those of the female pale 

 grey. The sexes of our beautiful forest-dwelling moths Azelina gallaria 

 and A. ofhio'pa differ in size, colour, and wing-outline. Declana glacialis, 

 a brilliant day-flying mountain species, which almost certainly mimics the 

 distasteful species belonging to the genus Metacrias, has the male much 

 more brilliantly coloured than the female, and this is almost certainly due 

 to the operation of sexual selection. 



In the family Tortricidae remarkable sexual disparities exist in certain 

 species belonging to the genus Harmologa, which are found high up on our 

 southern mountains, and fly rapidly in the hottest sunshine. Of these 

 probably the largest and handsomest species is Harmologa trisulca, recently 

 discovered at Arthur's Pass. The male is a very rich reddish-brown with 

 a vivid orange-yellow longitudinal stripe on the forewings, the hindwings 

 being dark greyish-brown. In the female the forewings are dull ochreous 

 and the hindwings pale straw-colour. The other mountain species of the 

 genus exhibit a similar class of colouring, but in the lowland species, which 

 fly at dusk or by night, the difference between the sexes is unimportant, 

 and the males are not more brilliantly coloured than the females. 



Our largest native lepidopteron, the well-known Hepialus virescens, 

 exhibits most striking sexual differences in wing-outline, colouring, and 

 markings. AH, these characters are, in the female, more concordant with 

 the usual type of the genus than in the male, and it is a fair inference that 

 the peculiarities of the male have been more recently acquired. The general 

 colouring of both sexes of Hepialus virescens is equally protective when the 

 insect is resting amongst foliage ; but probably that of the male is more 

 beautiful, and certainly brighter, than that of the female, and hence may 

 have arisen t;hrough sexual selection. In connection with our insect, it 

 may perhaps be of interest to mention that in its close British ally 

 the Ghost-moth {Hepialus humuli) all the wings of the male are snow- 

 white, the forewings of the female being dull-yellowish and the hindwings 

 grey. Of this species Mr. Richard South tells us that the males may be 

 seen in the evening, sometimes in numbers, in grassy places, swaying 

 themselves to and fro without making progress, and appearing as though 

 they dangled from the end of an invisible thread ; the female flies 

 straight, and, as a rule, in the direction of one or other of the pendulous 

 males.* In this case it would appear that the unusual disparity in colour 

 between the sexes has been beneficial to the species in enabling the female 

 to discover the male, a reverse arrangement to that usually subsisting. 

 In the Shetland Islands the white male of the Ghost-moth is usually 

 replaced by a variety {thulensis) in which the male is coloured very 

 similarly to the female, and this is explained by the fact that in that 

 northern latitude the summer nights are never dark, and the conspicuous 

 white colouring of the male is not necessary. 



In many species of moths, especially those having females of obscure 

 or retiring habits, the antennae of the males are heavily branched on each 

 side, or, as it is technically termed, bipectinated, those of the female being 

 slightly branched or simple. In these species the males have the power 

 of discovering a female even when situated at a considerable distance. 

 Collectors habitually turn this fact to good account, for if they happen to 



* R. SotfTH, The Moths of the British Islands, ser. 3, p. 361. 



