Monkeys, rats, and parrots are here and in all tropical countries
the subject of much complaint, and if the plantation is remote from
towns or in the forest, their depredations can only be held in check
by the constant presence of well-armed hunter or watchman. Of the
more serious enemies with which we have to deal, pernicious insects
and in particular those that attack the wood of the tree, everything
has yet to be learned.
Mr. Charles N. Banks, an accomplished entomologist, now stationed
at Maao, Occidental Negros, is making a close study of the life
history of the insect enemies of cacao, and through his researches
it is hoped that much light will be thrown upon the whole subject and
that ways will be devised to overcome and prevent the depredations of
these insect pests. The most formidable insect that has so far been
encountered is a beetle, which pierces and deposits its eggs within
the bark. When the worm hatches, it enters the wood and traverses it
longitudinally until it is ready to assume the mature or beetle state,
when it comes to the surface and makes its escape. These worms will
frequently riddle an entire branch and even enter the trunk. The
apertures that the beetle makes for the laying of its eggs are so
small--more minute than the head of a pin--that discovery and probing
for the worm with a fine wire is not as fruitful of results as has
been claimed.
Of one thing, however, we are positively assured, i. e., that the
epoch of ripening of the cacao fruit is the time when its powerful
fragrance serves to attract the greatest number of these beetles
and many other noxious insects to the grove. This, too, is the
time when the most constant and abundant supply of labor is on the
plantation and when vast numbers of these insects can be caught and
destroyed. The building of small fires at night in the groves, as
commonly practiced here and in many tropical countries, is attended
with some benefits. Lately, in India, this remedy has been subject
to an improvement that gives promise of results which will in time
minimize the ravages of insect pests. It is in placing powerful
acetylene lights over broad, shallow vats of water overlaid with
mineral oil or petroleum. Some of these lamps now made under recent
patents yield a light of dazzling brilliancy, and if well distributed
would doubtless lure millions of insects to their death. The cheap cost
of the fuel also makes the remedy available for trial by every planter.
There is a small hemipterous insect which stings the fruit when about
two-thirds grown, and deposits its eggs within. For this class of
insects M. A. Tonduz, who has issued publications on the diseases of
cacao in Venezuela, recommends washing the fruit with salt water, and
against the attacks of beetles in general by painting the tree stem and
branches with Bordeaux mixture, or with the vassiliére insecticide,
of which the basis is a combination of whale-oil soap and petroleum
suspended in lime wash. There can be no possible virtue in the former,
except as a preventive against possible fungous diseases; of the
sanitive value of the latter we can also afford to be skeptical, as
the mechanical sealing of the borer's holes, and thereby cutting off
the air supply, would only result in driving the worm sooner to the
surface. The odor of petroleum and particularly of whale-oil soap is
so repellent, however, to most insects that its prophylactic virtues
would undoubtedly be great.
The Philippine Islands appear to be so far singularly exempt from
the very many cryptogamic or fungous diseases, blights, mildews,
rusts, and cankers that have played havoc with cacao-growing in many
countries. That we should enjoy continued immunity will depend greatly
upon securing seeds or young plants only from noninfested districts or
from reputable dealers, who will carefully disinfect any shipments,
and to supplement this by a close microscopical examination upon
arrival and the immediate burning of any suspected shipments.
Another general precaution that will be taken by every planter who
aims to maintain the best condition in his orchard is the gathering
and burning of all prunings or trimmings from the orchard, whether
they are diseased or not. Decaying wood of any kind is a field for
special activity for insect life and fungous growth, and the sooner
it is destroyed the better.
On this account it is customary in some countries to remove the fruit
pods from the field. But unless diseased, or unless they are to be
returned after the harvest, they should be buried upon the land for
their manurial value.