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mixture; (4) the efficiency of the spraying apparatus; and (5) 
the thoroughness with which the work is done. The frequency 
of showers will at certain times and in certain localities in Hawaii 
make spraying more difficult than elsewhere. 
In temperate climates much of the spraying is done during 
the winter at the time when the plants are not in leaf and then 
there is much less danger of damage to the plant. Since plants 
are continuously in leaf in Hawaii weaker mixtures must be used 
and a more persistent effort must be made to keep the plant feed- 
ing pests in check. 
Preventive measures are the keynote in insect warfare. It is 
easier to prevent an insect pest becoming established than to sup- 
press them by curative measures afterwards. Thorough cultiva- 
tion, selection of resistant varieties, the time of planting, supply- 
ing necessary plant food by fertilizers, the introduction of natural 
enemies, entomological quarantine, spraying before the pests be- 
come epidemic, are all measures that will tend to restore the 
"balance"' in favor of the plant. 
It is a fact accepted by economic entomologists without excep- 
tion, that a healthy plant can resist to a great degree the attack 
of an insect enemy. To bring about a healthy growth and pro- 
mote vigor, we must see that our plants receive a sufficient supply 
of water and plant food. Also in the various cultural practices 
we must consider their direct effect on the insect ^ests ; that is, 
to control an insect pest by cultural methods, implies more than 
the practice suitable for the plant itself. For example, in tillage 
it may be that as far as the plant requirements are concerned, onlv 
the surface of the soil need be kept in a friable condition, but I 
think it well to stir the soil frequently about fruit tiees to a con- 
siderable depth to break up the chambers of the ant nests about 
the roots since these insects are very active in the distribution of 
the scale insects. For the same reason it would be well to flood 
the area occasionally about the trees for a period of several hours. 
In pruning, furthermore, the purpose of the trees may not require 
leaving the center open so that a free access of light and air is pos- 
sible, but just this condition is unfavorable to the development 
of scales and mealy-bugs, and should be practiced. Also such a 
method of pruning makes thorough spraying possible. Enough 
has been said to show that cultural methods can be made an impor- 
tant factor in insect control. 
I have seen owners spraying for the Avocado Mealy-bug and 
allowing wild guava to grow about the place simply covered with 
the same insect. Obviously the guava should have been eradi- 
cated. If Hawaii is to become a fruit-producing country, it must 
of necessity learn the lesson of putting on the market not alone 
fruit, but clean fruit. All manner of places that will harbor insect 
pests must be done away with. Many plants of no economic 
importance are included in the list of food plants of many of the 
insect pests. What good to fight the pests on the cultivated plants 
