Contributions to Experimental Entomology 555 



below), for more than forty-eight hours, died.^ Still, very pro- 

 nounced cold, for example —15° C, never injured the pupae if 

 they were exposed to it only about an hour, even when the experi- 

 ment was repeated as often as three times daily for several succes- 

 sive days. Hence, J. coenia could not hibernate in the northern 

 states even as a pupa since a constant temperature of —5° C. or 

 below for several days is by no means rare in winter. 



Through the influence of cold the pupa takes on a very dark 

 ground color, while the white punctate markings increase in dis- 

 tinctness and also in size. If one exposes pupae to higher tem- 

 peratures ( +38° C. and above) all the colors pass over into a light 

 red in which one sees small black dots. In both cases the newly 

 acquired color persists till the butterfly hatches. 



If caterpillars attacked by flacherie still have the strength to 

 pupate, the progress of the disease becomes apparent in the color 

 of the pupa, which is a uniform blue-black. The decomposition 

 process is like that of the caterpillars. Just as caterpillars of all 

 ages may die of flacherie, the period at which it occurs in the pupa 

 also differs with different individuals. I had, for example, a pupa 

 which died about six hours before it should have hatched as a 

 butterfly. The head, thorax and legs were completely developed, 

 the marking of the wings was almost perfect, but the body was 

 decomposed. In this case, therefore, only the body of the animal 

 was affected with the disease, and this, for some peculiar reason, 

 had not spread to all parts of the pupa. But that the disease al- 

 ways first makes its appearance in the abdomen was shown by 

 the reddish pupas obtained from experiments with high tempera- 

 tures. When these had flacherie the progress of the disease from 

 the tip of the abdomen to the head could be accurately followed 

 in the increasing change of color. 



All the pupae used in the experiments and the control were kept 

 in the room at a temperature of about 22° C. and care was taken 

 to provide the necessary amount of moisture in the receptacles con- 

 taining them. All the butterflies hatched after being kept in the 

 room from ten to thirteen days, both the control pupae and the 



■In all experiments I used pupae that were lo to 12 hours old. Perfectly fresh pupse, with 

 their chitinous investment still soft, died within 12 hours at— 2° C. 



