THE WHITE-PINE WEEVIL 197 



the dead terminals on the trees, and if the fire were not too hot they 

 would be uninjured. This would result in an excessive number of 

 parasites and nearly a complete control in the burned area would result. 

 The superfluity of parasites in the burned area would find their way, 

 more or less, into the surrounding country and there would be an extra 

 heavy parasitization of weevils immediately surrounding the burn. 

 Where light brush fires are common year after year, as they are in 

 Minnesota, their effect on the weevil should be noticeable. Such fires 

 are, however, even more injurious to the pines than the weevil injury, 

 and burning for weevil control should, of course, never be resorted to. 

 The difference in the silvical habits of the white pine may have an 

 influence. It has been noticed repeatedly that the weevil almost never 

 attacks young pines growing in the shade of other trees, even though 

 the shade be light. In Minnesota, while much reproduction is found 

 in the open, it is much more commonly found under a light shade of 

 aspen, birch, or sometimes jack pine, and often occurs in mixture with 

 Norway pine. In the East the best stands of reproduction are pure 

 stands in the open and a much smaller per cent is found doing well 

 in mixture with, or in the shade of, other trees. 



Ages Attacked 



The first attack of the weevil occurs when the pines are from 5 to 

 7 years old. The first year the infestation is usually very light, but 

 increases from year to year until the maximum is reached, when the 

 trees are about 15 years old. From then on the amount of infestation 

 decreases until the attack finally ceases between the 25th and 30th years. 



Preferences of the Weevil 



It has been the observation of all who have noticed the injurious 

 work of this weevil that it shows a decided preference for pure stands of 

 pine growing in the open. With increasing amounts of shade the weevil 

 injury decreases in proportion to the density until the injury is reduced 

 to zero under a shade such as that cast by an average stand of oak or 

 maple. 



In pure stands in the open, where its attack is most severe, the white- 

 pine weevil shows a preference for certain trees. Suppressed trees are 

 practically never attacked, while the greatest infestation is found among 

 the dominant and codominant crown classes. It seems to select for 

 attack the most thrifty and the most rapidly growing trees in a stand. 

 This habit of selecting the best trees sometimes retards the process of 

 natural thinning by reducing the height growth of the tallest trees and 



