364 Forestry Quarterly. 



der fires numerous and severe, especially so in young growth 

 where they often burn into the crowns. In old stands, par- 

 ticularly if there is no reproduction on the ground, they are con- 

 fined 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 

 thousands 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 at- 

 tacks 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 

 pilifera Winter, ) speedily stains the sapwood ; the other, the 

 Red-Rot (Polyporus ponderosa von Schrenk,) follows after a 

 longer interval, and causes the wood to decay. Other fungi at- 

 tack live trees, but are not important here. 



Insects The chief insects infesting dead timber are, in the 

 Black Hills, arnbrosia beetles and the larvae of Cerambycid and 

 Buprestid beetles. 



Hopkins lists two ambrosia beetles, Gnathotricus sidcatns Le- 

 Conte, and G. occidentalis Hopkins, as occurring on beetle in- 

 fested 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 heart- 

 wood. They cultivate a fungus in their burrows which stains the 

 adjacent wood. These burrows also serve as a means for the ex- 

 tension 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 growing season, and 

 to hibernate in their burrows during the winter, several gener- 

 ations are doubtlessly produced in a season. 



More important than the ambrosia beetles are the deep-wood 



