December, '13] WOLCOTT: WEST INDIAN AND DEMERARAN NOTES 449 



in the morning and noon. They are usually seen in the fields of young 

 ratoon cane, where the eggs may be deposited. No baits seem to 

 have any particular attraction for them, but the moths are not par- 

 ticularly difficult to catch on the wing. Gangs of boys, armed with 

 home-made butterfly nets patrol the fields of young ratoon cane and 

 have little difficulty in capturing fifty or seventy-five in a day. 



In young cane, where the stalk is not large, the entire shoot is 

 killed by Castnia, the larva retreating into the stool and going into 

 another shoot to complete its development. In fields of young cane, 

 the boys going through, cutting out the dead hearts caused by Diatrcea, 

 are also able at the same time to cut out the shoots injured by Castnia 

 and capture the larva inside. Three years ago, and more, when 

 Castnia was a much more serious pest than it is now, the price set for 

 the larvae was one cent each. The amount of money the boys w^ere 

 able to earn by cutting out giant borer larvae was so great that the 

 insect received the name of "gold-digger." Another opportunity the 

 boys have of collecting the ''gold-digger" is after the cane is cut for 

 the mill, when the conspicuous black hole in the stubble of the cane 

 shows where a fully grown larva is hidden in the stool below. Very 

 few larvae are ever found in the cut stalks, as the larva retreats into 

 the stool when it becomes aware of the approach of the cane cutter. 

 The tunnels are considerably larger in proportion to the size of the 

 insect than are those of the smaller moth borer and the insect can 

 move in them more quickly. 



Mr. J. J. Quelch told me of fields where Castnia injury had been 

 particularly severe and wholesale methods of destruction had been 

 necessary. After the cane w^as cut, the field was flooded for several 

 weeks entirely killing out all Castnia larvae and pupae present in the 

 stools. 



Three years ago the injury by the giant moth borer to cane all 

 over Demerara became so severe that strenuous measures had to be 

 adopted. It was at this time that the four control measures above 

 described were tested out and found to be thoroughly practical and 

 satisfactory. They are as follows: 



(1) Collecting of the adult moths in butterfly nets. 



(2) Cutting out the young larvae in the young ratoon cane. 



(3) Cutting out the older larvae and pupae from the stools of cane 

 after the crop has been harvested. 



(4) In the case of very heavy infestation, the flooding of the entire 

 field after the cane is cut. 



The control thus obtained is not permanent and is maintained only 

 by the persistent enforcement of these regulations, even at times 

 when Castnia has become comparatively scarce. No outbreak need 



