F-517833 
FIGURE 4.—Mist blower applying insecticide to pine trees in a seed orchard. 
—a period during which a large number of new insecticides and 
methods of application have come into extensive use, and during 
which outbreaks covering hundreds of thousands of acres of forest 
have been suppressed. As effective as insecticidal control has 
been, however, it has not proved to be an unmixed blessing. It has 
given rise to many complex problems associated with known or 
suspected adverse side effects caused by some of the more com- 
monly used chemicals. This stems from the fact that these chemi- 
cals, like most other chemicals used as insecticides, are non-specific 
and can be expected to be harmful to at least some other exposed 
animal species. The problem is compounded in that some chemical 
insecticides are very persistent, that all of the material applied in 
a given environment may not remain in that environment and 
that free-ranging animals cannot be excluded from sprayed areas. 
Public awareness of known and possible hazards associated with 
the use of these chemicals in insect control projects, therefore, 
has given rise to a considerable degree of concern over their con- 
tinued widespread use. 
Efforts are unceasing to discover and develop new and safer 
insecticides and to determine the danger points of insecticidal 
accumulations in the tissues of various forms of wildlife, as a 
basis for preventing undesirable damage to the biota. Application 
techniques and equipment are being refined in order to provide 
better control of the placement of insecticides in the environment 
and to further lessen the dangers of undesirable side effects. 
Studies are being made to improve sampling and biological evalu- 
ation techniques as a basis for improving the timing of application 
and to insure that insecticides are applied only when and where 
they are needed. 
The rapid changes occurring in the development and use of 
insecticides in forest insect control make it inadvisable to include 
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