280 COCOA 



CHAP. 



"mosquilla" does not live on other parts of the cocoa, 

 but its effect would be lessened by the presence in or 

 near the cocoa fields of trees or shrubs which are also 

 liable to be attacked by the insect. Whether the 

 " mosquilla " attacks other plants besides cocoa is not 

 yet known ; indeed our knowledge of the insect is still so 

 slight that it has not yet even received a scientific name. 

 Judging from the description, it would seem to be 

 allied with the Hdopeltis. 



(4) Caterpillars which eat the leaves are not of great 

 importance as enemies of the cocoa plant, which may 

 be considered to be remarkably free from this sort of 

 pest. In Surinam the very young leaves, when still 

 reddish and limp, are sometimes eaten by little cater- 

 pillars of an undetermined Geometride, and in Java a 

 few species of Limacodidae have been found attack- 

 ing the leaves (Orthocraspeda trima, Belippa lohor, 

 Parasa lepida). 



Thrips (Physopus rubrocinctd) is a very harmful 

 pest in the cocoa plantations in Surinam and the West 

 Indies. 



The life-history of this insect has not yet been 

 studied carefully. The adult insects as well as the 

 larvae live on the underside of the leaves and suck 

 the juice. The affected leaves become yellowish, with 

 numerous little brown spots ; they soon fall off, and if 

 the attack is severe, the tree generally is soon com- 

 pletely defoliated. The tree makes new leaves, but 

 frequently it happens that these are also attacked and 

 fall off again. Once more the tree tries to make new 

 leaves, but these are small and weak, and if other 

 conditions are not very favourable, the death of the 

 tree may follow. Often, however, the thrips does not 

 continue its attacks to this extent, but is still indirectly 

 the cause of the death of the tree, the weakened branches 

 being very liable to "die-back" disease (Diplodia 

 cacaoicola), and in Surinam it has often been found 

 that in fields first attacked by thrips a large number 

 of trees were lost by " die-back." 



