268 COCOA 



CHAP. 



The average number of eggs laid by one female, and the 

 average time which elapses between egg-laying and 

 hatching of the larvae, have not yet been definitely 

 ascertained. 



The tunnels made by the young larvae run close 

 under the surface of the bark. As the larvae grow 

 bigger the broader the tunnel, and finally it is as broad 

 as the bark, running close under the surface and enclosed 

 only by a thin layer of bark. From the outside the 

 presence of the borer is shown by the ejection of chips 

 of wood from the aperture of the tunnel, and often by 

 an exudation of gum. 



When the larvae are full grown after about 2 to 

 3^ months they bore into the wood and make an 

 oblong cavity, in which pupation takes place. Zehntner 

 calls this cavity " the pupal cradle." It is about 25 to 30 

 mm. (1 inch) long and 4 to 5 mm. broad. From this 

 cavity a narrow tunnel runs directly through the bark 

 to the outside, being closed only by a particle of saw- 

 dust, covered by a thin layer of bark, so that it can be 

 easily opened by the beetle when it issues from the 

 tree. The length of the pupal stage is about 15 to 

 20 days. After the beetle has issued from the pupa, it 

 remains some five days in the " pupal cradle " in order 

 to allow the chitin coat and especially the mandibles 

 to harden. So far as we know at present the beetle 

 lives about one month. 



Like most beetles, the larvae of which live as borers 

 in the cocoa, the Glenea beetle feeds by gnawing here 

 and there the bark of young cocoa twigs. 



The Java planter applies against this borer no other 

 measures than the. West Indian planter does against 

 his Steirastoma borer. The larvae are removed by 

 excision, and as many of the beetles as possible are 

 caught. Wherever this is done carefully, the pest is 

 kept within certain limits. For this purpose the larvae 

 have to be removed as early as possible as soon as a 

 few of the characteristic wood-particles are to be seen 

 on the bark and while the larvae are still young. 



