THE ENTOMOLOGIST. 



Vol. XXIV.] JANUARY, 1891. [No. 832. 



THE SEXES OF LEPIDOPTERA. 

 By W. F. de Vismes Kane, M.A., F.E.S. 



I AM surprised to find that Mr. Gockerell should have found it 

 necessary to defend the views he put forward in a former paper 

 (Entom. xxii. 177) as to the possibility of the sex being determined 

 in the embryo by external influences, especially food. The 

 hypothesis is now very generally accepted by biologists in relation 

 to animals in general, and may be found stated very clearly and 

 fully in a most interesting volume of the International Science 

 Series, ' The Evolution of Sex,' by Profs. Geddes and Thomson. 

 Mr. Wailly will find in Chap. IV. a reference to Lepidoptera, 

 Mrs. Treat's experiments and Mr. Gentry's opinion being cited. 

 A very strong case is made out in favour of the contention that 

 differences of nutrition, in conjunction with other conditions of 

 environment (chiefly bearing on assimilation probably) in the 

 larval or embryonic state, determine the sexual distinctions. 

 Evidence bearing on the subject is adduced from the life-history 

 of the tadpole, bee, aphis, and certain arthropods. I think most 

 practical entomologists' experience will, in a more or less degree, 

 bear out the theory. I venture to note one or two observations 

 of my own. I have observed in the South of France and in 

 Italy the dwarfing of L. icarus and astrarche, resulting from the 

 stunted condition of the food-plant produced by the climate and 

 dry soil, and not the less striking is the preponderance of males 

 over females in such localities. 



Again, in certain species, we find a vast disproportion in 

 number between the sexes. I would cite Thestor ballus. The 

 males emerge earlier than the females and enormously exceed 

 them in number. 



May it not be due to the innutritions foliage of the Lotus 

 hispidus growing in the arid localities where it is found, namely, 

 the parched hill- sides of South Europe ? 



ENTOM. — JAN. 1891. B 



