DISEASES AND ENEMIES 277 



insects by means of fire. For this purpose the labourers 

 use bamboo-sticks filled with kerosene or some other 

 similar oil and provided with a wick of cotton. The 

 fruits are treated with this torch, and a great number 

 of Helopeltis are killed. Some fly away in time, how- 

 ever, others are not reached by the fire, and a still larger 

 number on the twigs or branches are left unharmed. It 

 is worth mentioning that the fruits are not damaged in 

 any way by this method. As the insects like to retire 

 during the hotter hours of the day into shelter places 

 on the branches and under the leaves, the best time for 

 catching as well as for burning the Helopeltis is the 

 early hours in the morning. 



Other methods have also been tried. Spraying has 

 not yet given satisfactory results, but extensive and 

 conclusive experiments with different mixtures have 

 not yet been made. The insects are not attracted by 

 light, and lamps are therefore of no use for catching 

 them by night. Their natural enemies are few ; most 

 carnivorous insects dislike the Helopeltis and leave it 

 untouched, and only the spiders and Mantis eat a 

 small number of them. So far, no disease has been 

 discovered to attack the Helopeltis. 



One insect, however though not a real enemy, as 

 it does not attack the Helopeltis itself has been of 

 great use in combating this pest. It is a species of ant 

 (Dolichoderus bituberculatus Mayr), which, on some 

 plantations, has been introduced into the cocoa fields 

 with marked success. The ants were brought into the 

 fields in nests made of bamboo, and a certain number 

 of these nests were hung on every cocoa tree. In some 

 cases the fields have been populated successfully with 

 these ants, and where a great multiplication of the ants 

 was obtained, the number of Helopeltis was to a great 

 extent reduced, and the pest decreased in such a way 

 as to be no longer of great importance. On other 

 plantations, however, the introduction of these ants has 

 not met with such success. The cause could sometimes 

 be traced ; often the number of ants brought into the 



