454 



NELLIE M. PAYNE. 



to give comparable results with different species. The per cent, 

 of water before and during hibernation of three species of oak- 

 borers and of the Japanese beetle are shown in Fig. 4. 



The Japanese beetle larvae, Popillia japonica Neum. represent 

 an ecological group far more protected than either the oak- 

 borers or the woolly bear caterpillars. This species hibernates 

 in the ground below the frost line. About 97 per cent, are third 

 instar larvae and about 3 per cent, second instar. There is a 

 cyclic change in the cold hardiness of these larvae, not as marked, 

 however, as in the oak-borers but more apparent than in the 



PERIODICITY IN COLD HARDINESS 



40 



-35 



-30 



25 



-20 



-15 



-10 



-5- 



10 



UJ 

 EC 



I 



LJ 



10 





i 

 i 



i 



i 

 i 

 i 



i 

 i 



Dendroides canodenss 

 Popillia Japonica 

 Aquatic insects 



Sept Oct. Nov Dec Jan. Feb. Mar. Apr May June 



FIG. 5. Periodicity in cold hardiness. Dendroides canadensis - -, Popillia 

 japonica- , aquatic insects - . 



