54 COCOA 



CHAP. 



of these insects play a role of any importance in the 

 pollination. 



First, though the insects mentioned often occur on 

 cocoa, they are not invariably found on it. Thrips is 

 always, at least in the West Indies, a very noxious 

 insect, which happily does not occur on all cocoa trees ; 

 and the same may be said of the aphides, though they 

 do not cause as much damage as the thrips. There is, 

 however, another reason making it improbable that 

 they cause pollination. Cocoa is a plant showing strong 

 intercrossing. It is well known, for instance, that 

 varieties imported into Botanical Gardens produce seeds 

 which give rise to plants often showing unmistakable 

 characteristics of other varieties next to which they 

 have been planted ; while inferior varieties of Forastero, 

 planted between Criollo trees, give a progeny which 

 clearly shows Criollo characteristics. 



A study of the different types of Forastero also leads 

 to the conviction that many of them are hybrids. The 

 great number of types of Forastero, which contain the 

 different characteristics in all kinds of combinations, 

 cannot be understood without accepting a strong 

 inter-crossing between the different original Forastero 

 varieties. This subject is more elaborately treated in 

 Chapter V. 



This strong intercrossing indicates that the pollen 

 can be transported from one tree to another. The 

 transport might be effected in two ways, either by wind, 

 or by flying insects such as butterflies, wasps, bees, 

 flies but not by thrips, aphides, or ants, none of which 

 fly at all, and of which thrips and aphis can only 

 move very slowly. 1 



The question whether pollination takes place by 

 wind or by flying insects seemed at first difficult to 

 answer, because the flower of the cocoa does not appear 

 to be adapted to wind-pollinisation, and flying insects 



1 We may leave out of consideration the flying sexual individua of ants and 

 aphides, because they only appear at certain times and are not common 

 visitors of cocoa flowers. 



