October, 1929] 



WHITE PINE WEEVIL 



17 



the material under observation was examined only once each day, usu- 

 alh' in the morning. For instance, eggs may have been laid an hour af- 

 ter a fresh leader was introduced or an hour before it was removed. Like- 

 wise the eggs may have hatched only a few hours after they were exam- 

 ined. After some experience, however, it is possible to determine by 

 the appearance of the egg, or newly-hatched larva, the approximate ter- 

 mination of the incubation period. Since a large number of specimens 

 was used the results probably closely approach the length of the several 

 stages of development. 



Table II.— Length of (he Egg Stage, 1928 



