180 MISC. PUBLICATION 273, U. S. DEPT. OF AGRICULTURE 
damage or the course the epidemic may take if no control is under- 
taken, and conclusions as to the success of a bark-beetle project 
can only be deduced on the basis of an estimate of what would 
have happened if no control work had been undertaken. Control 
measures applied during the decline of an outbreak often tend to 
place an inflated value upon the results obtained. On the other 
hand, control undertaken during the time an outbreak is building 
to an epidemic may show little reduction in damage and give the 
appearance of failure. The best that can be done is to compare the 
trend of the epidemic on the treated area subsequent to control with 
that on a similar neighboring area where no work was done. 
To protect valuable forest areas from bark-beetle outbreaks cer- 
tain steps should be taken. These may be summarized as follows: 
(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 respon- 
sible for forest protection as to whether timber values in or adja- 
cent to the site of a detected outbreak warrant the probable 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 deter- 
mine (@) the trend of the outbreak and the possibilities of natural 
control; (6) The area involved in the infestation and threatened 
by it; (¢) 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 complete information 
furnished by the extensive survey, a decision can be reached as to 
the need and justification for applying artificial control measures, 
and whether or not the necessary cooperation of all affected owners 
can be obtained and the work adequately financed. If control work 
is decided upon, then— 
(3) A control campaign should be outlined and prompt and thor- 
ough control measures should be applied to all units showing epi- 
demic 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 destruction 
by bark beetles, incipient outbreaks must be promptly discovered and 
reported. If such asystem is consistently carried 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 
