86 



CACAO. 



THE CACAO BEETLE (Steirctstoma depressum, L.). 

 Coleoptera. 



The cacao beetle (Fig. 95) is perhaps the most serious 

 insect pest of cacao in the West Indies. The egg is laid in 



or on the bark, often in the angles 

 formed by the larger branches. 

 Stubs left in pruning, and any 

 wound of a tree, seem to attract 

 the egg-laying females. The 

 grub reaches a length of about 

 Ij inches when it is full-grown. 

 It is whitish in colour with 

 a small, dark-brown head. The 

 pupa is formed in the tunnel 

 made by the larva. The adult 

 is a black and grey beetle about 

 f-inch in length, with long, 

 slender antennae. The location 

 of the grubs under the bark of 

 the cacao tree is often indicated 

 by a dry, shrunken appearance. 



Control. The grubs of the cacao beetle may be dug out, 

 or killed by probing with a wire. Carbon bisulphide may 

 also be found useful in this connexion. When the beetle 

 grubs are dealt with, all dead bark and wood should be 

 removed and the healthy wood which is exposed should 

 be tarred or painted. The adult beetles may be trapped. 

 In the early morning they may often be found resting 

 on the trunks and larger branches of the cacao trees 

 where they may be collected, and killed by throwing them 

 into water to which a small amount of kerosene has been 

 added. In Surinam, the bark of the silk cotton tree is 

 tied on to the cacao trees to furnish hiding places for 

 these beetles. These hiding places are examined regularly 

 and the beetles collected. In Trinidad, trap pieces of the 

 Wild Chataigne or * Chataigne Moron ' (Pachira aquatica) 

 have been found very useful. The freshly cut pieces of 

 Chataigne which are pla.ced in the cacao tree provide the 

 female beetles with a suitable situation for egg laying, 

 and the eggs are laid in the traps instead of in the cacao 

 trees. In Grenada, branches which are removed from the 

 trees in pruning are left on the ground for a few days. 



95- Cacao beetle. 

 Adult and larva. Natural size. 

 (Imperial Dept. Agric.) 



