450 NELLIE M. PAYNE. 



not self dehydrating to any large extent. Thus the Japanese 

 beetle, Popillia japonica Newm., does not exhibit any marked 

 body weight changes over winter when kept in moist sur- 

 roundings, but can be experimentally dehydrated to half its 

 body weight. When thus treated they are very cold resistant, 

 having a survival temperature of as low as - - 28 C. In contrast 



900 \ 



\ 

 \ 

 \ 



600 v . 



700 



FALL DEHYDRATION CURVES 



OF TWO SPECIES OF 



CATERPILLARS 



laia 



400 ^V Diacrisia virginica 



300 



200 



1 00 



' 4567 



TIME IN WEEKS 



FIG. i. Fall dehydration curves of two species of caterpillars, Isia Isabella and 

 Diacrisia virginica. 



to the Japanese beetle larvae there are some species of oak borers 

 and caterpillars which are normally self dehydrating during the 

 winter. The dehydration curves (Fig. i) of Isia Isabella Hy. 

 Edw. and Diacrisia virginica Fabr. show a marked water loss as 

 these caterpillars go into hibernation. At the period of inflection 



