20 



however, in Phlceosznus cristatus an enemy which, under especially 

 favorable conditions, might prove quite destructive to standing timber. 

 At present this insect is attracted to the bark of felled trees in which 

 it breeds in great numbers. A Cerambycid bark borer, Callidiimi 

 janthinum, was also found under the bark of a felled tree, and may 

 be a common enemy. 



The Western yellow pine. — This is widely distributed through north- 

 ern California, Oregon, Washington, Idaho, and many other places 

 wherever the soil and climatic conditions are favorable to its growth. 

 Indeed, it is one of the commonest and most valuable timber trees of 

 the region. From the evidence found it has probably a greater num- 

 ber of insect enemies than any of the other trees mentioned, and at 

 present is suffering far more from their ravages. It has in Dendroc- 

 tonus brevicomis a most pernicious enemy, which penetrates, and 

 excavates winding galleries through, the living bark of the finest 

 trees, thus speedily causing their death. Very many trees have died 

 and are dying from this cause, and the dead ones are contributing to 

 the spread of forest fires. Its next greatest enemy is the pine but- 

 terfly, which has, from time to time, defoliated and caused the death 

 of much of the best yellow-pine timber in eastern Washington and in 

 Idaho. 



There are many secondary enemies of greater or lesser importance 

 among the Scolytid genera Pityophthorus, Pityogenes, Xyloterus, 

 Tomicus, Hylastes, and Hylurgops, which contribute to the death of 

 trees primarily injured by defoliating and other insects, fire, and other 

 causes. Numerous Buprestid and Cerambycid enemies of the wood 

 and bark contribute to the unhealthy condition of the timber and the 

 destruction of the wood. A lepidopterous larva infests the terminal 

 twig of young trees near Moscow, Idaho, and one or more Curculionid 

 beetles breed in the bark at the base of }^oung and old trees. 



The sugar pine. — While this, one of the most valuable timber trees 

 of California and southern Oregon, is in a more healthy condition 

 than the yellow pine, it has a dangerous enemy in an undescribed 

 Dendroctonus as well as in the destructive enemy of the latter. It 

 has also a host of other enemies which infest the twigs, bark, wood, 

 and roots. 



The silver, or western white pine. — This is a very common and most 

 valuable tree in eastern Washington and in Idaho, and has a special 

 enemy in the same undescribed Dendroctonus that infests the sugar 

 pine. A vast amount of dead timber was found in groups and scat- 

 tered through the forests in the vicinity of Kootenai and Sandpoint, 

 Idaho, which showed good evidence, in the great abundance of gal- 

 leries of this insect in the bark, that they had been killed by it. A 

 Tomicus, closely allied to confusus, was also found to be a very com- 

 mon enemy, entering the living bark of recently felled trees; as was 



