10 



BULLETIN 243, U. S. DEPARTMENT OF AGRICULTURE, 



growth when attack is made (PL IV, fig. 2). Yellow-pine cones, 

 however, do not fall from the trees, and after they turn reddish 

 brown in color they can be readily distinguished against the green 

 foliage (PL IV, fig. 1). After the yellow-pine cones become dried 

 they can not be broken readily from the limbs and quite often will be 

 found still adhering many years after the beetles have abandoned 

 them. The seeds may be formed, but they are invariably hollow in 

 blighted cones (PL IV. fig. 4). 



Occasionally a yellow-pine cone will be found that has been at- 

 tacked by the beetle in which the new brood has failed to develop. 

 The number of overwintering adults counted in the cones varied from 

 1 to 20, the average being from 5 to 8. The cone, however, is always 

 killed and the damage is just as great. 



The broods overwinter in the cones on the trees and emerge the 

 following spring. (PL IV, fig. 4.) Adults do not appear to remain 

 entirely dormant during this period, but feed to some extent on the 

 dry scales and seeds. Mortality of the new broods, to any extent like 

 that in the sugar pine, has not been observed. An examination of 

 many infested cones of the 1913-14 crop shows that over 90 per cent 

 of the new broods are alive. 



AMOUNT OF DAMAGE. 



The damage by the western yellow-pine cone beetle to yellow pine 

 has never been noted to be as extensive as that of the species working 

 in sugar pine. In heavy stands the loss to yellow pines is not so 

 noticeable as it is on open isolated trees. Even in these isolated trees 

 the amount of damage varies to a great extent on individual trees. 

 Isolated trees at lower elevations, especially those bearing heavy cone 

 crops, suffer most. 



Two trees standing close together were selected and the cones 

 counted as follows: 



Tree 

 No. 



Green cones. 



Beetle-killed 

 cones. 



Total. 



1 



2 



515 

 700 



448 

 65 



9C3 

 765 



The count was made August 5. 1914, at Ashland, Oreg. It shows 

 how damage may vary with individual trees. 



Estimates of the damage by this beetle necessarily depend upon the 

 same factors as those pertaining to sugar pine. The damage, Iioav- 

 ever, can not be confused with that of squirrels, as the beetle-killed 

 yellow-pine cones adhere to the trees, while the squirrels invariably 

 cut and either eat or cache the cones. -(PL V, fig. 2.) 



