CiiAp. VIII. Proportion of the Sexes. 25 1 



iiere add, that in I^yperythra, a gpniis of moths, Giionfe aavB. that 

 from four to five females are seat ' iii oolloctious from India ibr one 

 ,uiale. 



When this subject of tlie proportional numljrTS of the sexes of insects 

 was brougut before the Entomological Society," it was generally 

 admitted that the males of most Lepidoptera, in the adult or ima;;c 

 state, are caught in greater numbers than the females : but this fact 

 was attributed by various observers to the more retiring habits of 1hu 

 females, and to the malps emerging earlier from the cocoon. This 

 iHtter circuiiistunce is well known to occur with most Lepidoptera, ^'8 

 well as with otlnr in,-ects. So that, as M. Personnat remarks, the 

 niale.-> of tlie domesticated Bombyx Tamamai, are useless at the liegin- 

 iiiiig of the season, and the females at the end, from the want of 

 mutes.*" I cannot, however, persuade myself tliat these causes sufKce to 

 explain tl.e great excess (jf males, in the above oases of oert-dii butter- 

 flies which are extremely common in their native countries. Mr. 

 Stainton, who has paid very close attention during many years to the 

 smaller moths, informs me that when he collected them in Ihe imago 

 state, he thouiiht that the males were ten t'mes as numerous as the 

 females, but thiit since he has reared them on a Inrge scale tinm the 

 eaterpiUur stHte. he is convinced that tlie females arc the iiKire 

 numerous. Several entomologists concur in this view. JMr. Double- 

 day, however, and some others, take an opposite view, and a e con- 

 vinced that they have n ared from the eggs and caterpillars a larger 

 proportion of males than of females. 



Besides the more active haljits of the males, their earlier em rg nee 

 from tlie c.coon, and in some cases their frequenting more npen 

 stations, o.her causes may be assigned for an apparent or real difference 

 ill the propuriional numbers of the sexes of Lepidoptera, when cap- 

 tured in the imago st,,te, and when reared from the egg or cateipiKar 

 state. I hear from Professor Canestrini, that it is believed by many 

 breeders in Italy, that tlie female caterpillar of tlie silk-moth suff-is 

 more from the recent disease than the male ; and Dr. Stand. nger 

 informs me that iu rearing Lepidoptera mure females die in the 

 cocoon than ma'ea. With many species the female cateipillar is la'-ger 

 than the male, and a collector would naturally choose the finest 

 specimens, and thus unintentionally collect a larger number of females. 

 Three collectors have tidd me that this was their practice; but Dr. 

 Wallace is sure that most collectors take all the specimens which they 

 can find of the rarer kinds, which alone are worth the trouble of 

 rearing. Birds when surrounded by caterpillars would probably 

 devour the largest ; and Professor Canestrini informs me that in Italy 

 some breeders believe, though on insufficient evidence, that m the first 

 broods of the Ailanihus silk-moth, the wasps desti oy a largei' number of 

 the female than of the mule caterpillars. Dr. Wallace further remarks 

 that female caterpillars, from being larger than the males, require 

 more time for their development, and consume more food and mois- 

 ture ; and thus thi y would be exposed during a longer time tti 

 danger from ichneumons, birds, &c., and in times of scarcity would 

 Derifh in gre.aer numbers. Hence it appears quiie possible thai 



" ' I'roc. Entomolog. Soc' Feb. ' Proc. Ent. Soc' 3rd series, vol, v 

 lUh, 1868. 18li7, p. 487. 



•' (juoteil by Dr. Wallace iu 



