1922] 



Frost: Ecdysis in Tmetocera ocellana 



167 



way off the head and the skin had worked part way off the 

 body so that the prothoracic shield rested over the second 

 abdominal segment. At 4:55 P. M. of the same day the head 

 capsule was cast and at 4:59 P. M. the larva succeeded in 

 freeing itself from its skin. 



NUMBER OF MOULTS. 



The number of moults apparently varies in different parts 

 of the country. Mr. G. E. Sanders (1919)* found in Canada 

 that there are only seven moults. The majority of the larvae 

 entered their winter quarters in the third instar, while a few 

 moulted a third time and entered hibernation as fourth instar 

 larvae. In Pennsylvania the writer has obtained ten larval moults. 

 The majority of the larvae enter hibernation in the ninth instar, 

 the other two moults occurring the following spring. A small 

 percentage hibernate in the eighth instar. Considerable varia- 

 tion may be expected where the number of instars are as high 

 as in the Bud-moth. 



MEASUREMENT OF HEAD CAPSULES. 



In moulting, the head capsule and thoracic shield, because 

 of their chitinous nature, retain their original shape and thus 

 lend valuable characters for a study of this kind. Advantage 

 was taken of this fact and the head capsules of a number of each 

 instar were preserved and measured. 



Table of Measurements of Head Capsules of T. ocellana Schiflf. 



* Cornell Bull. 50, 1893. 



