December, '12] buttrick: black hills timber insects 457 



Forest Officers for all signs of beetle infestation, and all infested trees 

 are at once cut and the bark destroyed. 



A leaf scale, probably Chionaspis pinifolice, occurs, chiefly on seed- 

 lings and saplings. Its attacks are sometimes fatal. However, so 

 long as it is not more abundant it need not be regarded as dangerous ; 

 perhaps it is slightly beneficial, since it usually occurs in dense over- 

 stocked thickets of young growth, where a thinning is badly needed. 



The dry climate and the character of the forest operate to render 

 fires numerous and severe, especially so in young growth where they 

 often burn into the crowns. In old stands, particularly if there is 

 no reproduction on the ground, they are confined to the surface and 

 do less harm. Fires burning through irregular stands where the 

 flames mount into the tops of the smaller trees, kill most of the stand 

 but destroy little timber. 



Destruction of Fire-Killed Timber. As a result of fires many thou- 

 sands of feet of otherwise merchantable timber are killed annually. 

 Much of this is never used. A knowledge of the rate of its subsequent 

 destruction and methods of preventing it would result in saving much 

 of it, thus reducing the drain on the live timber of the region. 



Both insects and fungi attack trees killed by fire, their attacks being 

 to some degree interrelated. 



Fungi. Von Schrenk has given an account of two important fungi 

 attacking beetle-killed trees, and they are also found on trees killed 

 by fire. One, the "blue" fungus {Ceratostomella pUifera Winter), 

 speedily stains the sapwood; the other, the Red-Rot {Polyporus pon- 

 derosa von Schrenk), follows after a longer interval, and causes the 

 wood to decay. Other fungi attack live trees, but are not important 

 here. 



Insects. The chief insects infesting dead timber are, in the Black 

 Hills, ambrosia beetles and the larvae of Cerambycid and Buprestid 

 beetles. 



Hopkins lists tAvo ambrosia beetles, Gnathotricus sulcatus LeConte, 

 and G. occidentalis Hopkins, as occurring on beetle infested pine in 

 the Black Hills. It is probable that these are the forms which occur 

 on fire-injured and killed trees. Their attacks seem more apt to be 

 directed towards injured than dead trees. 



Ambrosia beetles bore in sapwood and to a less extent in heartwood. 

 They cultivate a fungus in their burrows which stains the adjacent 

 wood. These burrows also serve as a means for the extension of the 

 ''blue" fungus. The seasonal history for the species in the Black 

 Hills has not been worked out in detail. The adults, however, seem 

 to fly throughout the groAving season, and to hibernate in their burrows 



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