I go: 



FORESTRY AND IRRIGATION. 



459 



ble extent, it is very difficult to esti- 

 mate exact!}' the amount covered b}^ 

 this pest, and the above estimates are 

 largely guesswork. Nevertheless the 

 matter is truly serious, and in some dis- 

 tricts, particularly in the Spearfish 

 region, large areas of forest have ceased 

 to be green and offer onh' shades of red 

 and brown, the trees over extensive 



tracts having been killed. 



According 



years, but whether it is now at a stand- 

 still or decreasing in the rapidity of its 

 spread is uncertain. But, whether still 

 increasing or not, there is no doubt that 

 the beetle today is ruining timber at a 

 rate entirely out of proportion to the 

 growth, and, unless its work can be re- 

 stricted, there is danger of the larger 

 part, if not all, of the forest being de- 

 stroyed. 



Courtesy U. S. Department of Agriculture. 

 THIS IHUSTRATION SHOWS HOW BARK BEETLES MARK THE SURFACE OF WOOD. 



to Dr. Hopkins, the beetles attack the 

 trees during the summer, and hibernate 

 generally in the tender larval (grub) 

 state and swarm the following year. 

 The trees thus attacked remain green 

 for some time and do not die until the 

 year after the attack. Once attacked, 

 practically all the trees succumb. Ap- 

 parently the pest has rapidly increased 

 in its destructiveness for a number of 



Since the large amount of dead tim- 

 ber remains standing and sound for 

 some time, there is a great and constant 

 danger of fire becoming the ally of the 

 beetle, and thus finish whole townships 

 in a sweep. At present the dead timber 

 far exceeds in amount the timber in- 

 fested and in various stages of injur}-, the 

 two kinds comparing probablyfive toone. 



Thus far no important steps have 



