Forest Insect Surveys 
It has long been recognized that successful control of forest 
insect outbreaks depends not so much on the control method used 
as upon a knowledge of the insect situation on immediate, sur- 
rounding areas. When an outbreak is discovered, it needs to be 
known whether it is increasing or decreasing. It is also impor- 
tant to locate the center of greatest concentration and to deter- 
mine the direction of spread (169). When an outbreak occurs, it 
is also important to know the value of the resources at stake and 
the status of natural control factors, before decisions to apply 
control are made. Of like importance is the possession of a 
general knowledge of insect conditions throughout a timber type 
or region. This is helpful in developing plans for the detection of 
outbreaks in their early stages, a time when they may be sup- 
pressed most easily and economically and before heavy losses are 
incurred. Similarly, it is helpful to have a continuing record of 
the presence and abundance of the less spectacular, non-outbreak 
types of insects, to determine if, when, and where their numbers 
or damage are reaching economic levels of concern. Where inten- 
Sive management of the forest for timber or other objectives is 
being practiced, it is also important to have up-to-date informa- 
tion on all destructive pests to allow for their early control where 
needed. Such knowledge as described above is sought or acquired 
through surveys. 
Forest insect surveys of one sort or another have been made in 
the United States since the early days of this century (88), but 
prior to the passage of the Forest Pest Control Act in 1947, they 
were usually conducted on a more or less unorganized basis. Pas- 
sage of the Act made it possible for the first time to conduct 
surveys on an organized, systematic basis on forest lands of all 
ownerships. In part, the Act authorized the Secretary of Agri- 
culture, either directly or in cooperation with other Departments 
of the Federal Government, with states and other public agencies, 
and with private organizations and individuals, to conduct surveys 
to detect and appraise insect infestations before they develop to 
outbreak proportions; to appraise their potential destructiveness ; 
and to determine the needs for their control. Forest insect surveys 
are also conducted in Canada. There, the aim is not only to detect 
and appraise infestations but also to obtain information on the 
distribution, biology, and cycles of abundance of insect species 
for taxonomic and other purposes (481). 
Basically, forest insect surveys are of two kinds, detection and 
evaluation, and they may be conducted separately or at the same 
time. Detection surveys, as the term applies, are primarily for the 
purpose of discovering threatening infestations. Evaluation sur- 
veys are usually far more intensive and complex, being concerned 
with such factors as the intensity and trends of pest populations, 
the identification and evaluation of natural control factors, the 
size and boundaries of infestations, the value of the resources at 
stake, the possibilities of economic loss and an estimate of its 
magnitude if suppressive measures are not taken. 
Many methods and techniques are employed in conducting sur- 
veys, the choice depending on many factors, such as the insect 
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