COISTE BEETLES. V 



Yellow-pine cones are sessile; that is, instead of being attached, 

 each to its individual stalk, they are set closely to the limbs. At- 

 the beginning of the second-year growth they are from 1 to 1J inches 

 long. Necessarily the initial point of attack must differ from that 

 on sugar-pine cones. The adult enters the cone by penetrating the 

 scales very close to the base of the cone. Sawdust borings may be 

 seen on the surface of the scales and quite often a tiny pitch tube 

 collects around the entrance of the burrow (PI. Ill, fig. lb'). The 

 adult does not turn directly outward through the central axis of 

 the cone, but bores completely around the axis, forming a short spiral 

 tunnel (PI. Ill, fig. 2). This spiral twist of the tunnel before the 

 beginning of the egg gallery is not noticeable in sugar pine, but it is 

 characteristic of attack in yellow pine. Its result is completely to 





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Fig. 1. — Comparative life history of the sugar-pine and yellow-pine cone beetles, 

 piled from field records. (Original.) 



Com- 



CUt off the nourishment and insure the deadening of the cone, which 

 produces the condition necessary for the development of the larvae. 

 After completing this girdle at the base of the cone the adult extends 

 the egg gallery out through the central axis (PL III, fig. 3). Ovi- 

 position (PI. Ill, fig. 4), development of larvae (PI. IV, fig. 3), and 

 transformation from pupae to adults are in all important respects 

 the same as with the sugar-pine cone beetle. 



In a few instances attacks have been observed on the small, first- 

 year cones just after they " put on." This seems to be a rare habit, 

 and has only been observed where there is a great scarcity of second- 

 year cones. Eggs are not deposited and broods can not develop in 

 these small cones. 



Beetle-killed yellow-pine cones A^ary from 1 to 4 inches, the length, 

 as in sugar-pine cones, depending largely on the stage of second-year 



