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UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 243 



Contribution from the Bureau of Entomology 

 L. O. HOWARD, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



July 24, 1915. 



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CONE BEETLES: INJURY TO SUGAR PINE AND 

 WESTERN YELLOW PINE. 



By John M. Miller, 

 Entomological Assistant, Forest Insect Investigations. 



INTRODUCTION. 



A class of damage which has been termed " blighted cones " occurs 

 frequently in the seed crops of sugar pine throughout its range in 

 California and Oregon and of western yellow pine in the Pacific 

 coast and southern Rocky Mountain regions. This damage is dis- 

 tinguished by the dying of the immature cones soon after the start- 

 ing of the second year's growth. The dead blighted cones, which 

 are less than one-half the size of normal cones, are withered and 

 faded to a reddish brown. The blighted sugar-pine cones fall to the 

 ground during the first summer, whereas the blighted yellow-pine 

 cones may adhere to the branches for several }^ears. 



INSECTS CAUSING DAMAGE. 



The greater part of this damage 1 is caused by small scolytid 

 beetles, which have been identified by Dr. A. D. Hopkins, of the 

 Bureau of Entomology, as Conophthorus spp. The common name of 

 " cone beetles " seems most appropriate for these insects, as their life 

 history and the damage caused by them relate entirely to the cones 

 of the host trees. 



The adults are small, black, cylindrical beetles, from 3 to 4 mm. 

 in length. The adult beetle bores a small tunnel through the axis 

 of the cone, wherein the eggs are deposited. The larvae, tiny white 

 grubs from 3.5 to 4.5 mm. in length when full grown, feed upon the 

 scales, seeds, and tissues of the withering cone. 



The pupae, which differ but little in size and color from the larvae 

 but possess the form of the adult, are formed within the same cone 



1 The caterpillars of certain cone^ moths also kill immature second-year yellow-pine 

 cones, in such a way that the damage resembles the work of the cone beetle, but this 

 damage may be readily recognized by the character of the attack. In the areas observed 

 by the writer the cone worms cause less than 10 per cent of the blighted cones. 



Note. — This bulletin is the result of field observations made in Oregon and California. 

 It is suitable for distribution on the Pacific coast. 

 92232°— Bull. 243—15 



