08 



infested localities canes should not follow canes on 

 the same land in the same year, and that when intervening 

 crops are planted these should not be Indian corn, Guinea 

 corn or sweet potatoes, as the roots of all of these are 

 readily eaten by the root borer. The second recommenda- 

 tion is that all stumps in infested fields should be dug 

 out, broken up and burned, as soon as possible after the 

 crop is harvested. The breaking up of the stumps exposes 

 many of the grubs to attack by natural enemies such as 



blackbirds and ants, and the burn- 

 ing of them will have an additional 

 useful effect in connexion with the 

 control of the root disease of sugar- 

 cane. Carbon bisulphide and a 

 solution of cj^anide of potash have 

 been tried for the control of the 

 root borer. These are applied by 

 injecting them to a depth of 8 or 10 

 inches in the soil by means of 

 a special injector. Poisonous fumes 

 are given off, and are supposed to 

 soil, killing any grubs with which 

 they come into contact. The experiments so far carried 

 out have not given results which justify the recommenda- 

 tion of the expensive practice of soil injection. As far 

 as Barbados is concerned, the impervious nature of the 

 soil in those localities where trials have been made of 

 carbon bisulphide and cyanide of potash probably very 

 largely reduces the effectiveness of these insecticides. 



During the present year (1011) large numbers of the 

 adult of this insect have been collected on estates in Bar- 

 bados, by children, and destroyed. On account of favour- 

 able rains in February and March, it was possible to plant 

 Indian corn on an estate in that island, where the attacks 

 of root borer had been very severe in the ripening cane, so 

 that fields from which the canes had been reaped were 

 planted with this crop ; in June it was found that the root 

 borer weevil was hiding among the leaves of the corn plants 

 in considerable numbers. Collecting was at once begun, 

 and during a period of about four weeks some 30,000 of the 

 insects were captured and destroyed on one estate; on 

 other estates the collecting was carried out to a much 

 smaller extent. The beetles were found hiding among 

 the leaves of the pigeon pea, sweet potato, and bonavist 



Fig- 73- Grub of 

 , root borer. 

 Enlarged. 

 {Imperial Dept. Agric.) 



travel through the 



