Outside of certain insects of the order Coleoptera, cocoanuts in
the Philippines are reasonably free from enemies; in some districts,
close to forest-clad areas, the raids of monkeys do some damage. A
tree-nesting rat, which nibbles the young nuts, is also a source of
considerable loss. The rat is best overcome by frequent disturbance of
his quarters. This involves the removal of the dead leaves and thatch
that form constantly about the base of the crown. But the wisdom of
this recommendation will depend entirely upon circumstances. As the
planter may find that rats or the rhinoceros beetle are the lesser
evil, so should he be governed.
There are localities in the Archipelago where the plague of rats
is unknown and where the beetles abound. In that case it would be
unwise to disturb the leaves which are very tardily deciduous and
do not naturally fall till the wood beneath is hard, mature, and
practically impervious to the attacks of insects.
Where rats are numerous and insects few, which is the case in some
localities, the dead and dying leaves, among which the rat nests,
may be advantageously cleared away whenever the tree is climbed to
harvest the fruit.
Among serious insect enemies we have to contend largely with the very
obnoxious black beetle, Oryctes rhinocerus, and, fortunately, to a
lesser extent, with Rhynchoporus ferrugineous (probably the same as
R. ochreatus of Eydoux), while R. pascha, Boehm, and Chalcosma atlas,
Linn., are also said to appear occasionally.
However different their mode of attack, the general result is the
same, and their presence may surely be detected by the appearance of
deformed or badly misshapen or lacerated leaves.
The attacks of all species are confined to the growing point and as
far downward as the wood is tender and susceptible to the action of
their powerful mandibles.
The black beetle makes its attacks when fully mature, eating its way
into the soft tissues and generally selecting the axil of a young
leaf as the point of least resistance. Others simply deposit their
eggs, which hatch out, and the resulting grub is provided with jaws
powerful enough to do the same mischief. Two or three of these grubs,
if undisturbed, are sufficient in time to completely riddle the
growing tip, which then falls over and the tree necessarily dies.