INBREEDING OF JUNONIA COENIA UNDER 



HIGH TEMPERATURES THROUGH 



TWENTY-TWO SUCCESSIVE 



GENERATIONS 



WILHELM SCHRADER 

 LOS ANGELES, CAL. 



Breeding butterflies in liot and cold temperatures is not a new idea. German 

 entomologists, especially, have experimented in that line for many years, and 

 have publislied tlieir experiments, and I have no doubt they will be followed by 

 many interested entomologists, who have the time and patience. I hope that my 

 little experience publislied here, will interest others in joining me in this most 

 interesting work, in which, to obtain best results, many students of widely separ- 

 ated regions must co-operate. I wisli to thank Mr. Fordyee Grinnell, Jr., of 

 Pasadena, Cal., for his valuable help. 



In the spring of the year 1906 I sowed some seed of Liiiaria cymhalaria, .a 

 little trailing plant, which is very useful for rockwork, and found later on this 

 |)lant some caterpillars, at that time unknown to me. I gathered all I could fiifd, 

 and obtained later sixteen chrysalides. As I had contemplated for some time prior 

 to try some temperature experiments, I bought a little chicken incubator, and bred 

 the chrysalides in 90 degrees warm, damp air, and in darkness. After five days the 

 butterflies emerged, and they were all our well-known Junonia coenia. I noticed 

 that all were somewhat dark in the ground color. However, I was disappointed. 

 As is the case with all experimental work, we commonly expect great things, so 

 much the more when we read condensed accounts of what other experimenters 

 have accomplished. Yet it is a great thing to have patience to try things out, 

 so I figured that all our thousands of different species of butterflies were not 

 made at once ; they must have developed by the slow process of evolution. 



Anybody who is interested in insect life will have marveled how quick the 

 transformations from the egg to the imago take place in nature. In the summer- 

 time with us, this cycle is repeated once, and by some butterflies twice. However, 

 what will our readers say, to hear that by the use of artificial warmth, I was able 

 to breed from the first generation in April, 1909, to November, 1911, that is, 

 within two years and seven months time, twenty-two successive generations ; and 

 by keeping the caterpillars in 80 to 90 degrees temperature day and night, I 

 succeeded, in a few generations, in finishing a complete cycle in one month. This 

 could not be kept up as trouble arose with contagious diseases. Other experi- 

 menters have made temperature experiments, by breeding butterflies in artificial 

 temperatures, hot as well as cold, and we have learned many new facts; yet 

 there is still much to learn, as almost every experimenter formed a somewhat 

 different theory, as to why these changes in color and markings, from the winter 

 to the summer generation, take place. I have not heard that any experimenter, 

 liere or abroad, has succeeded in breeding from his own stock of butterflies at any 



