THE ENTOMOLOGIST. 



No. 124.] DECEMBER, MDCCCLXXIII. [Price Od. 



Contrulling Sex in Butlerjiies. By Chas. V. Riley, M.A.* 



(Entom. vi. 372.) 



The article with the above title by Mrs. Mary Treat, in 

 the March number of the ' Naturalist,' has attracted a 

 good deal of attention, and most naturalists will be proud 

 that a lady has set the example of making such investigations. 

 But while I fully concur with the authoress in the deduction 

 that the female in insects, and especially in Lepidoptera, 

 "requires more nourishment than the male," I cannot follow 

 her in the other conclusion, "that sex is not determined in 

 the Q^g of insects." Were this conclusion well founded it 

 would upset what most physiologists of note believe to be a 

 fundamental principle, ^'^^., that, in the individual, sex is 

 determined at the moment of conception, no matter at what 

 stage of growth it becomes ascertainable by us. That such 

 is the case with the higher animals will scarcely be doubted, 

 and to reason from analogy that it is the case with the whole 

 animal kingdom is quite as natural, though equally as unsafe, 

 as it was in years gone by to argue that liicina sine concubitu 

 was an impossibility, or that larval reproduction, in insects, 

 could not possibly take place. It is, therefore, worth while 

 to weigh the evidence for and against the possibility of con- 

 trolling sex in larvae. 



Mrs. Treat, whom I know to be a good observer, and 

 whom I esteem as a correspondent, had already, in 1871, 

 communicated to me her belief that she could control the 

 sex in butterfly larvae, and though I then gave her my 

 opinion that her experiments were by no means satisfactory 

 and conclusive, for the reason that many of the larvae 

 * Eeprinted from the ' American Naturalist,' September, 1873. 

 VOL. VI. 2c 



