CONE BEETLES. 



the remainder of the summer and the long overwintering period 

 (PL II, fig. 4). 



The new adults are not entirely dormant during this period, but 

 feed to some extent on the dead tissue of the cone, as is apparent 

 from the sawdust borings. The number of overwintering beetles 

 which have been counted in a single cone varies from 1 to 36. The 

 average, however, is from 6 to 10. 



A considerable percentage of these blighted cones will always 

 be found in which the beetles have made the attack and completed 

 the egg gallery, but the larvae have failed to develop. This failure of 

 the broods is found more often in the very small and in the largest 

 cones which have been attacked. The most successful attacks are 

 found in the intermediate sized cones from 4 to 6 inches in length. 

 Some of the larger cones appear to resist the beetles by drowning 

 them out, as some trees are capable of resisting barkbeetles. In every 

 attack, however, the cone is killed. 



On certain areas great mortality to the new broods of the cone 

 beetle, presumably through the work of an entomophagous fungus 

 as yet not specifically determined, has been observed. In many 

 of the cones the brood reaches the stage of full-grown larvae, pupae, 

 or even new adults, and then dies. On an area near Sisson, Cal., in 

 1913, over 50 per cent of the cones contained these dead broods. 

 On one area near Colestin, Oreg., in 1914, the brood developed in 

 only 57 per cent of the attacked cones. The mortality of the de- 

 veloped broods amounted to 62 per cent, so the broods were finally 

 successful in but 21.6 per cent of the cones attacked. The cause of 

 this has not been determined and will require further study before 

 conclusions can be drawn, although material illustrating the mortal- 

 ity of broods was sent in during the summer of 1914 and referred 

 to the Bureau of Plant Industry. While it appeared to be an en- 

 tomophagous fungus it has not yet been reported definitely. Few 

 parasites of this cone beetle have been found. 



All evidence points to the existence of but one generation of this 

 species annually. The broods develop successfully only in the imma- 

 ture cones between 2J and 8 inches in length, The period during 

 which the cones may be found in this stage is so short that it allows 

 for the development of one generation only. In August, 1913, an 

 emergence of a considerable portion of the new generation of beetles 

 was noted in northern California and southern Oregon. No subse- 

 quent attacks were observed on the nearly mature cones of the 

 1913-14 crop or upon the newly formed 1913-14 cones. No similar 

 emergence was observed in 1912 or 1914, and the only explanation 

 that can be given for the 1913 emergence was that it was abnormal, 

 probably due to the unusual wet-weather conditions of that season. 



