THE FAUNA OF THE CACAO FIELD 113 



fumigation with carbon bisulphide, and may sometimes 

 be probed with wire, and the hole effectively sealed with 

 cement or a dry wood plug. Whatever method is used 

 the great object should be to wound the tree as little as 

 possible. It is a curious fact that the attack of the borer 

 is generally coincident with the appearance of fungus 

 disease, and it has been asserted that unless fungus is 

 present the attack of the borer will not be severe. The 

 writer has seen numerous instances where the evidence 

 tended to confirm this view. The attack of the borer is 

 always most prominent on badly drained ground, where 

 the trees are wanting in vitality, and growth not up to 

 the standard. The adult winged insects are readily caught 

 at certain seasons on the stems and branches, especially 

 in the early morning. They may also be trapped by 

 tying a bandage round the stems with opening below, 

 under which the insect will secret itself. The planter 

 should satisfy himself, when an attack takes place, that 

 there are no natural breeding-places in or near his fields, 

 as they infect many forest and economic trees as well as 

 cacao. Fallen branches and stems should be removed 

 from the field and destroyed, as these form hiding-places 

 for the insect, which must be regarded as one of the major 

 pests of the cacao field. 



No. 4. Trachyderus succinctus is the name of another 

 boring beetle which has been seen to do similar damage. 



Nos. 5 and 6. The "Pin-hole" Borer {Xyleborus 

 perforans) does but little damage, except where trees are 

 in a bad condition of health and severely attacked by 

 wound fungi. A similar insect known as Tomicus species, 

 is another small borer which does similar damage. The 

 attack of these insects may be controlled by maintaining 

 good field hygiene and increasing the vitality of the trees 

 by good cultivation. The removal and destruction of all 

 dead limbs from the trees and from the ground is a stern 

 necessity. 



Nos. 7 and 8. " Sawyers " or " Twig girdlers " {Ecthoea 

 ^Uftdricprnis an(^ Endesmus grisescms) have hg-bits much 



