90 DISEASES 



been recommended as a combative measure. It is sug- 

 gested that seriously attacked trees, which appear to be 

 dying, should be cut off 18 in. from the ground and the 

 top of the stumps coated with tar. 



INSECTICIDES 



Many of the insect pests previously described cause 

 very little damage to cocoa trees, but others, like thrips 

 and the Steirastoma larvae, have caused serious damage 

 where no attempts were made to exterminate them. 



The fact that a particular insect pest has hitherto not 

 proved troublesome affords no criterion of its capa- 

 bilities in this respect should conditions more favourable 

 for its multiplication occur. The planter should be 

 constantly on the look-out for possible pests, and when 

 found prompt measures should be taken to exterminate 

 them. In order to be in a position to adopt rational 

 remedial methods it is necessary that the planter should 

 be equipped with the various insecticides which have 

 proved beneficial in checking cocoa pests and also with 

 suitable apparatus with which to apply them. Different 

 insects injure the trees in different ways, and a method 

 of attack which would be attended with excellent results 

 when applied to check the ravages of one insect might 

 be futile against those of another. 



The principal insect pests of cocoa may be classed into 

 three main divisions : Boring insects, sucking insects, 

 and leaf -eat ing insects. 



Boring Insects. Under this division may be included 

 the various larvae of Longicorn beetles and termites ; the 

 means of combating both these pests have already been 

 dealt with. 



Sucking Insects. These suck the plant juices by means 

 of a slender tube which they insert into the tissues of 

 the plant. Plant lice (Aphides), mealy bugs, scale insects, 

 etc., are comprised in this division. To exterminate 

 these, insecticides known as " contact poisons " are 

 generally applied, which kill the insects when the poisons 

 come in contact with their bodies. The following are 

 some of the mixtures most generally employed for this 

 purpose : 



Resin Wash. Thoroughly pulverise 4 Ib. of resin and 



