372 THE ENTOMOLOGIST. 



Controlling Sex in Butterjlies. By Mrs. Mary Treat * 



That sex can be conlrolled in butterflies I think I have 

 demonstrated by careful experiment the past season ; acci- 

 dent first prompted the experiment. Two years ago this 

 past summer I was feeding a fe\v larvae of Papilio Asterias for 

 the cabinet, when one of my specimens wandered from its 

 food, and rested upon a book to undergo its transformations. 

 Not feeling inclined to give up the book to this purpose, I 

 placed the larva on a fresh stem of caraway: upon removing 

 it from the book I found its feet were entangled in silk, and 

 that it was in position for a chrysalis, but not yet fastened; 

 so I was surprised to see it commence eating. It continued 

 eating some days longer, before changing to a chrysalis. I 

 then tried others in the same way, and also took off quite a 

 number of larvae, shutting them away from food. Some of 

 the larvae that I deprived of food in this first experiment 

 died, but all that completed their transformations were 

 males; while those that 1 induced to go on feeding, by 

 templing them with the best and freshest food, proved to be 

 females. 



This season (1872) I commenced with the larvae the 17th 

 of June, and continued feeding broods of different ages 

 through the month of July. Early in July I had about two 

 hundred larvae feeding at the same time. The room in which 

 I conducted my experiment faced east and south, and toward 

 noon, of each of those excessively hot days in the early part 

 of Jul}', it was several degrees warmer than in the outside air. 

 The food-plant on which I fed the various broods was placed 

 in jars of water, which were set in a large box partly filled 

 with earth, the whole being covered with deep blue mosquito- 

 netting; heat and moisture seemed favourable to health and 

 rapid growth. 



On the 25ih of June one lot of eggs hatched, on the 10th 

 of July they were chrysalides, and on the 18lh of the same 

 month the butterflies appeared, only requiring twenty-three 

 days for the complete transformation. On the other hand, I 

 have had this same Asterias butterfly eleven months in 

 coming to maturity ; some larvae that hatched in August, 



* Eeprinted from the ' Amei-ican Naturalist,' vol. vii. p. 129. 



