INSECT ENEMIES OF EASTERN FORESTS 51 
INSECTICIDAL CONTROL OF INSECTS IN THE FOREST 
By (S:; BH. Porrs 
The control of insects in the forest is a different problem from the 
control of those same insects attacking shade trees. In the forest. 
where relatively low values are at stake, the basic aim is prevention 
of unusual losses or of the spread of outbreaks; whereas in shade or 
park trees, where individual trees are readily reached and represent 
relatively high values, direct control to check immediate damage is 
desirable. Consequently, a distinction between forest and shade trees 
is maintained throughout the following discussion. 
In the forest there is recognized a normal or endemic type of in- 
festation by many insects that feed on trees and shrubs, causing only 
shght damage and against which the cost of artificial control would be 
unwarranted. Control is therefore confined to the prevention of 
threatened outbreaks and the suppression of those that have attained 
destructive proportions. 
Many artificial control methods that have proved to be effective are 
discussed in the following pages. 
SPRAYING AND DUSTING 
CAUTION 
It should be clearly kept in mind that most of the substances 
under consideration are poisonous. If they were not, they would 
probably be useless against the insects for which they are rec- 
ommended. Therefore the recommendations for the proper use 
of these substances should be followed. Careless, unnecessary 
exposure and misuse is fraught with hazard. Splashing of liquid 
on the skin or inhalation of dust while handling dry powders 
should be avoided. Containers that have been used for mixing 
or applying chemicals should be stored in a safe place, if they 
are to be used again, or destroyed. Any excess liquid left after 
treatment is completed should be disposed of by digging a pit into 
which the chemicals can be poured and covered with soil. Such 
liquids should never be poured into streams or ponds where they 
will endanger humans, livestock, or fish. 
Chemical sprays or dusts may be apphed for the direct control of 
defohating, sucking, and certain other insects, such as twig-infesting 
forms that pass a part of their life cycle on the surface of the plant. 
Although spraying and dusting are important methods of control 
where valuable shade and ornamental trees are involved, they have 
not had wide application in the forest, except where insect eradication 
was the objective or in serious outbreaks in recreational areas, water- 
sheds of reservoirs, or areas where the timber was especially valuable. 
So many different factors affect the cost of spraying that no definite 
cost figures can be given. The total cost of treatment depends on the 
size of the trees and the density of the stands, the accessibility of the 
area to be treated, the availability of suitable equipment, and the cost 
of labor and materials. Usually where the trees are being grown for 
a timber crop, their value will not warrant much expense for spray- 
ing. With the improvement of distributing apparatus for some of the 
