130 



THE SCOLYTID BEETLiBS. 



aggregating approximately 1,200 acres, although it is probable that 

 the insect was present before the fire occurred. He states as follows : 

 Two or three years after the fire serious work of the insect was first made apparent, 

 and local observers state that the beetle work has steadily increased until the entire 

 spruce stand is threatened with insect destruction. In his 1904 report Mr. F. G. Plum- 

 mer stated, "Notwithstanding the fact that the summits of the Sierra Blanca afford 

 apparently ideal conditions for the growth of the spruce, about 20 per cent of the 

 standing trees are dead or dying. This gives the forest the appearance of having been 

 scorched by a fire not severe enough to utterly destroy it. For this no cause was found. 



Pig. 81.— Average-sized Engeltnami spruce tilled by fire and tlie Engelmann spruce beetle. Lincoln 

 National Forest, at elevation of 10,160 feet. (Original.) 



The insect work occurs at an elevation above 9,000 feet and will probably extend 

 to the altitudinal limit of the spruce in case it has not already done so. It was found 

 in trees varying from 6 to 20 inches, which had not been subject to other injury. 

 Approximately 1,000 acres of the headwaters of the South Fork of the Bio Bonito 

 have been completely killed by the combined effect of fire and insects, and other 

 similar areas exist in the reserve. 



Mr. F. G. Plummer, of the Forest Service, in a report entitled 

 "Forest conditions in the Lincoln National Forest, New Mexico"" 

 estimates a total stand of 29,027,000 feet, board measure, on 13,142 

 acres. Of this, 1,480 acres, or about 9 per cent, has been burned. 



^Professional Paper No. 33, series H, Forestry, 11, U. S. Geological Survey. 



