460 COCOA 



CHAP. 



may be regarded as amounting to a little more than 

 200 kilograms per acre. 



To the regular field work of the plantation belongs also 

 the fight against pests and diseases (see Chapter VIII. ). 



One pest has to be combated on all plantations, 

 namely, the larvae of the cocoa beetle (Steirastoma 

 depressum). These occur during the whole year, 

 boring channels through the branches and the stem. 

 They have to be cut out with a knife. For this purpose 

 a regular gang of trained grub-collectors (" wurmen- 

 zoekers ") is employed, and after the close of the day's 

 work these labourers have to show what they have 

 collected. Sometimes they are paid simply by day- 

 task, but sometimes they are paid per piece, or per 

 weight of grubs collected. 



As pointed out in Chapter VIII. , not only the larvae 

 but also the beetles are harmful, and to eradicate the 

 pest not only the larvae, hidden in the wooden parts 

 of the trees, but also the beetles have to be caught. 

 These are fiying from tree to tree, well protected by 

 their greyish colour, resting here and there, gnawing 

 at the bark of the young twigs, and the females 

 depositing their eggs in crevices or holes of the bark. 



In order to catch these beetles, the Javanese 

 immigrants found out a handy method. They noticed 

 that the bark of the wild " cotton tree,' 1 or, as the 

 negroes call it, " cancantree " (Bombax ceiba), had a 

 special attraction for the beetles, and on pieces of this 

 bark attached to the branches of cocoa trees soon a 

 certain number of beetles were to be found, apparently 

 attracted by the odour of the bark. In this way a 

 great number of beetles were easily caught. 



There are different species of cocoa beetles, but 

 by far the most common is Steirastoma depressum 

 (Fig. 87), the larvae of which construct their channels 

 rather superficially, at any rate not deep in the trunk 

 of the trees. 



In neglected fields this beetle causes an enormous 

 damage, and its presence is at once visible by the great 



