6 4 
GENERAL TREATMENT OF INSECT PESTS. 
This paper contains brief directions as to the means to be adopt- 
ed for the destruction of garden and crop pests. In such small 
space elaborate methods, applying to special cases, cannot be dis- 
cussed but the directions given may be modified with discretion 
and rendered applicable to ordinary insect diseases. Many of the 
remedies described are derived from the published work of ento- 
mologists in other parts of the world and are such as have been 
found to give the best result under the conditions obtaining in the 
West Indies. 
Determination of the cause of Disease. 
When a plant is supposed to be diseased, it should be carefully 
examined to find the cause of the injury and any unusual appear- 
ance should be noted. There may be some difficulty in discover- 
ing, with certainty, the real -source of damage but a thorough exam- 
ination of the plant, in cases where the disease is not at once 
apparent will, as a rule, reveal the true nature of the injury and its 
cause. It is of no use to assign the damage to the first or to anv 
insect that may be found on the plant, and if treatment is adopted 
for the wrong class of pest the best results are not likely to be 
obtained. 
Insect Pests. 
Plants are attacked by diseases and pests of very various kinds, 
of which insects form a large proportion. Speaking generally, 
harmful insects may be divided into three classes according to 
their mode of attack : — 
fi) Leaf-eating insects. 
(2) Boring ,, 
(3) Sucking ,, 
Leaf-eating Insects may be taken to include those that feed on 
the leaves and other exposed parts of the plant. Caterpillars 
(“ worms ”) are the most common, and grasshoppers often do a 
considerable amount of harm. A Well known instance of caterpil- 
lar attack is found in the Para Rubber tree whose leave s are some- 
times eaten by large numbers of caterpillars. Other familiar in- 
stances are the caterpillars that attack the water-lemon vine, cantia, 
arrowroot, tobacco, sweet potato and cassava. As a rule each 
kind of caterpillar confines itself to one food or to closely related 
plants. 
Boring Insects feed inside the tissues of plants, spending the 
greater part of their lives securely hidden. All parts of plants are 
attacked, the plaintain weevil living in the roots or in the part of 
the stem below the ground, the cocoa beetle tunnelling in the 
trunk and branches, and the coffee-leaf miner boring in the leaves 
are familiar examples. Other boring insects live in dried grain, 
tobacco, nutmegs, furniture, etc. 
Sucking Insects are, at the present time, the most destructive 
insert pests in the West Indies. They include -the plant lice 
(Aphidae) the mealv-wings (Aleurodidae), and the scale insects 
