LIFE HISTORY OF SHORTLEAF PIKE. 35 



fire is chiefly responsible. The heaviest direct injury to the stand 

 occurs just after the ages of 8 to 12 years, because prior to this time 

 the young forest is quickly restored by its power of coppicing. 

 Repeated burnings, however, cause a setback which the tree is able to 

 make up only in part. In older trees the effect of frequent fires is 

 cumulative in weakening the tree at its base, resulting in its over- 

 throw during high wind. Although not so complete in the case of 

 shortleaf as in that of the more resinous longleaf, the sort of decima- 

 tion of stands is continuous and rapid where fire occurs frequently. 

 External injury and loss in vitality, due to excessive heat, open up 

 avenues of ready attack by insects and fungi. 



Ordinary surface fires usually develop sufficient heat to kill back 

 trees up to 6 or 8 feet in height, and to inj.ure trees from about 7 to 12 

 feet in height. Basal fire scars heal rapidly, and during intervals 

 between fires thrifty pole and standard trees usually succeed in com- 

 pletely covering them. Such cases are quite frequently noted in ex- 

 amining the tops of stumps. The damage and loss due to fire is mainly 

 in the form of defective lumber and reduced yield per acre from the 

 stand, which may be ascertained by measuring the yields from well- 

 stocked groups selected within a stand and comparing them with its 

 total yield. The wide difference between the two is perhaps the most 

 impressive measure of the beneficial effect of protection, since fire can 

 safely be considered one of the most active causes of the poorly 

 stocked condition of our forest stands. 



INSECTS' AND MAMMALS. 



Of all insects, the southern pine beetle {Dendroctonus frontalis 

 Zimm.) is undoubtedly the most injurious to shortleaf pine. It is 

 active throughout the warmer portions of the year, passing through 

 the bark to the cambium, or living layer, and there eating out long, 

 winding furrows or egg galleries, which partially girdle and weaken the 

 tree. The eggs hatch into grubs, which feed on this tissue, completing 

 the girdling and destroying the tree. Serious invasions of this insect 

 occurred in 1890, 1893, and 1910. The last outbreak led to a special 

 study by the Bureau of Entomology, whose report, 2 describing fully 

 its life history and giving recommendations for controlling the insect 

 pest, may be obtained upon application to the Division of Publica- 

 tions, Department of Agriculture, Washington, D. C. It has been 

 demonstrated that using trees that die in the fall and early winter for 

 fuel or other purposes during the winter serves both to control the 

 beetle and to prevent its outbreak. This is an important point to 

 bear in mind in handling shortleaf stands. 



1 For further information in regard to causes of injury by insects, apply to the Office of Insect Investiga- 

 tions, Bureau of Entomology, U. S. Department of Agriculture. 



2 Farmers' Bulletin 476, "The Dying of Pine in the Southern States: Cause, Extent, and Remedy," 

 U. S. Department of Agriculture. Also, Bureau of Entomology Bulletin 83, Part I, "Bark Beetles of the 

 Genus Dendroctonus," by Dr. A. D. Hopkins, p. 56. 



