INSECT ENEMIES OF WESTERN FORESTS 227 



To protect valuable forest areas from bark-beetle outbreaks 

 the following steps should be taken : 



(1) A general reconnaissance or detection survey of valuable 

 forest types subject to bark beetle epidemics should be made each 

 year to detect the beginning of any outbreak. If an outbreak is 

 indicated, a decision should be reached by the owners or those 

 responsible for forest protection as to whether timber values in 

 or adjacent to the site of a detected outbreak warrant the prob- 

 able expense of a control operation. If so — 



(2) An extensive bark-beetle survey should be undertaken, 

 usually under the supervision of a competent forest entomologist, 

 to determine (a) the trend of the outbreak and the possibilities 

 of natural control; (b) the area involved in the infestation and 

 threatened by it ; (c) what areas must be included in the control 

 program; (d) the number of trees that will require treatment, 

 and the area that must be covered in the first season; and (e) 

 the probable cost and results to be expected. In the light of the 

 information furnished by such a survey, a decision can be reached 

 as to the need and justification for applying control measures, and 

 whether or not the cooperation of all affected owners can be ob- 

 tained and the work adequately financed. If control work is decided 

 upon, then — 



(3) A control campaign should be outlined and prompt and 

 thorough control measures should be applied to all units showing 

 epidemic trend within the project area. This should be followed 

 by treatment of such outlying areas as may jeopardize results 

 in the cleaned units. 



(4) A maintenance control program should be continued until a 

 natural balance has been restored. 



DETECTION OF BARK-BEETLE OUTBREAKS 



If forests are to be protected from serious damage or destruc- 

 tion by bark beetles, incipient outbreaks must be promptly 

 discovered and reported. If such a system is consistently car- 

 ried out, it will greatly reduce the ultimate cost of protection 

 and prevent the building up of disastrous and uncontrollable 

 infestations. 



The first reporting of outbreaks devolves upon the timber 

 owners, the State or Federal forest rangers, or others who are 

 primarily responsible for the protection of forests. Such work is 

 analogous to that of the forest-fire detection system. 



This detection work should be so planned that all valuable 

 forest types subject to bark-beetle outbreaks are given some 

 measure of inspection for insects each year. This work does not 

 need to be intensive, but at least it should disclose whether trees 

 are dying through any forest tract, and, if so, the probable 

 cause of death and the extent of the trouble. 



If trees are observed to be dying, either singly or in groups, 

 they should be examined and the cause of the trouble determined. 

 If there is no evidence of recent forest fires, insects may be sus- 

 pected. A closer examination of foliage, twigs, or bark should 

 show what primary insect is involved. The keys and accompanying 



