432 



Yearboo\ of Agriculture 1949 



classification of pine stands, known as 

 a hazard survey, has been carried out 

 only for a small part of the ponderosa 

 pine region. This work is basic to plans 

 for control through management and 

 is needed throughout much of the 

 western pine region. 



The possibilities for finding better 

 chemical methods for destroying bark 

 beetles have by no means been ex- 

 hausted. During the war, many new 

 insecticides came into prominence, 

 among them DDT, benzene hexachlo- 

 ride, and chlordane. They are now 

 being tested in forests, and it is prob- 

 able that a place will be found for 

 some of them in the control of bark 

 beetles. 



But the greatest hope lies in better 

 forest management. Pine silviculture 

 must take into account the habits of 

 the beetles themselves; by studying 

 this behavior, we should obtain a bet- 

 ter understanding of nature's methods 



of thinning, pruning, and harvesting. 

 Then, by "beating the beetles to it" and 

 imitating nature at her best, we should 

 be able to develop sound silvicultural 

 practices which will avoid further de- 

 struction from these small insects. 



F. P. KEEN, a graduate of the Uni- 

 versity of California, is senior ento- 

 mologist of the Bureau of Entomology 

 and Plant Quarantine in charge of the 

 Forest Insect Investigations Labora- 

 tory at Berkeley, Calif. His experience 

 with bark beetle problems in the west- 

 ern pine region covers 34 years. He is 

 author of a number of technical pa- 

 pers and bulletins on forest insects. In 

 1947 he received the Department's 

 Superior Service Award for his devel- 

 opment of a ponderosa pine tree clas- 

 sification, which is used as an index to 

 the susceptibility of pine stands to bark 

 beetle damage and as a guide to tree 

 selection on timber sales. 



INSECTS IN WOOD PRODUCTS 



THOMAS E. SNYDER 



Insects attack the forest tree in all 

 stages of its life, from seed to maturity. 

 The log that is cut from the tree also is 

 vulnerable in all its stages to attack by 

 other kinds of wood-boring insects 

 while it is still in the woods, while it is 

 green or seasoned lumber at the mill, or 

 is being stored, or, indeed, after it has 

 been put to use in a house, barn, or a 

 manufactured item. 



The insects that bore into lumber 

 cause losses of many kinds and degrees. 

 Sometimes much of the wood is riddled 

 by holes. Sometimes it is entirely pul- 

 verized so as to be completely unusable. 

 Sometimes only the quality of the wood 

 is lowered by the holes so that the grade 

 is reduced. Certain stain fungi, carried 

 by bark beetles and borers, discolor the 

 logs and lumber; they do not affect 

 performance, but the wood becomes 

 unsuitable for outside and decorative 

 purposes. After the lumber, pole, or 



other wood product is in use, insect 

 damage is even more serious, because 

 then the loss includes the costs of pro- 

 duction, seasoning, storage, and re- 

 placement. 



Two TYPES OF INSECTS are prima- 

 rily responsible. One requires wet 

 wood ; the other dry wood. Sometimes 

 the injury is one caused by the adult 

 beetles which fly to the log or lumber 

 and bore directly into the wood. At 

 other times the damage is caused by 

 the young hatching from eggs laid 

 under the bark or in the wood. 



Adult ambrosia beetles so-called 

 because they require green or moist 

 wood within which they raise fungi for 

 food rapidly penetrate green logs and 

 lumber. The males may assist the fe- 

 males in forming new colonies, and the 

 fungus is raised for the young to eat. 

 They have the beginning of a social 



