PART 1V. 
Reduviid bug, Rhinocoris tibialis, St., preys on adult Chilocorus lady- 
birds, and may at times work serious havoc among them, while a 
smaller bug of the same family, Ploiariodes sp., appears to specialize 
on the Psocids. 
But the real enemy of all, or at any rate of all the commoner 
predaceous insects, is a small Myrmecine ant, Pheidole punctulata, 
Meyr. This ant attends the coffee mealy-bug for .the sake 
of its sweet secretion. In so doing it in some way favours 
the growth of the mealy-bug—whether the actual attention of 
the ants is beneficial, or whether there is merely less mortality 
among the mealy-bug when the ants are present to act, as 
they do, as scavengers, is not quite certain. In any case, when kept 
in the laboratory completely protected from all natural enemies, the 
mealy-bug multiplies much faster in the presence of this ant. 
Again, this ant attacks and destroys most of, and possibly all, the 
beneficial predatory insects. It is at any rate known to kill the adults 
of Chilocorus and almost certainly their eggs, the adults of both 
species of Hyperaspis and the larve of Scymnus sp.; the larvae of 
Chrysopa sp., and the three commoner species of Psocids. Tt also 
destroys both adults and larve of the imported lady-bird Crypotolemus 
montrouzieri. 
Pheidole punctulata appears to be distributed over the greater 
part of the area where the common coffee mealy-bug is found, except 
that it is not yet known to occur west of the Karura river, and in this 
locality the mealy-bug, though it occurs sporadically, does not appear 
to assume the proportions of a major pest. It is here attended by a 
Camponotine ant which is presumably not so destructive as Pheidole 
to the predatory insects, and these always seem to be able to deal 
with an attack of mealy-bug by themselves. 
But where Pheidole occurs, such unaided natural control is 
impossible, as the ant breeds faster and increases with the presence of 
its favourite food, and the mealy-bug increases with the presence of 
the ant. 
It therefore appeared, and was subsequenty abundantly proved 
by experiments, that if the ants were denied access to an infected 
coffee tree, the mealy-bug would rapidly be destroyed by its enemies. 
Actually, under favourable conditions, almost complete ‘eradication of 
the mealy-bug is affected in about five weeks, though on some 
plantations, from causes which are at present obscure, a much longer 
time is taken. - 
There can however be no doubt but that this procedure of 
encouraging the already existing enemies of the mealy-bug is the most 
effective method at present known of combating this pest. The only 
alternative is spraying, and no spray can be expected to reach quite 
all the mealy-bugs on a coffee tree; while it will kill many of the 
predators and drive away the majority of the remainder. In point of 
fact, there are coffee plantations in this country which were sprayed, 
and though a temporary benefit was obtained, subsequently became 
infected worse than before. 
~~ The actual method of keeping the ants away from the mealy-bug 
1S.a more difficult matter. Poison baits, such as have proved 
Successful against the Argentine Ant (9, p. 12) and several others have 
been tried without success, as these ants learn by experience that the 
bait is poisonous, and once a few workers have been killed, refuse to 
* See list of references on page 194. 
195