THE SUGAR-CANE MOTH BORER. 43 



hearts" had not been cut out at that place. Individual fields at 

 Angola ran from 6 to 85 per cent, and at Port Allen from 9 to 

 94 per cent. 



It is possible that the different fields at Angola did not all re- 

 ceive exactly the same treatment as to cutting out the " dead hearts," 

 especially as the plantation is divided into a number of farms or sec- 

 tions, each of which has its separate manager. As far as the 

 authors could ascertain, however, the treatment had been uniform 

 over the whole plantation. 



It was the opinion of several of the farm managers that cutting 

 out the " dead hearts " would not be practicable on a plantation 

 where free convict labor is not available. 



Moore (104) records the collection of 15,285,960 larvae and pupse 

 of the moth borer on 17 estates in Demerara, British Guiana, in 1912, 

 and 13,632,655 in 1911. He then remarks : 



The effect upon the pest of all this terrific slaughter has not as yet been very 

 marked, but will increase more and more rapidly if the destruction be kept on 

 persistently, systematically, and relentlessly. The insect propagates at such a 

 very rapid pace, in spite of the counter-activity of a variety of natural enemies, 

 and in spite of whatever may be the weather conditions, when its seasons 

 come round, that to overtake it and bring it under proper control must needs 

 be a rather long undertaking. 



POISONING YOUNG PLANTS. 



By covering the young plants with an arsenical in powdered form, 

 which was suggested by the junior author, it was hoped to present 

 a poisoned leaf surface to the first young borers of the year. Before 

 gnawing into the plants the newly emerged larvse feed among the 

 leaf whorls for a limited time. It was thought that if they could 

 then be poisoned much damage later on could be prevented. 



A small preliminary experiment gave what seemed to be promis- 

 ing results, and in 1916 a large plantation experiment was planned. 

 Fields on a typical plantation were poisoned one, two, and three 

 times, powdered arsenate of lead being used, and the applications 

 being made at many different dates in the spring. After nearly 

 every application, however, there was a heavy rain, and the follow- 

 ing fall no benefit could be observed. About 2 pounds of poison 

 per acre were applied, a special horse machine being used. 



The experience gained in 1916 had proved that the machine, 

 which was designed for cotton, was not well adapted to sugar-cane 

 fields. In 1917 the framework was strengthened and a gasoline en- 

 gine added. This gave a much more uniform distribution of the 

 poison, and an application of 2 pounds per acre covered the plants 

 rather thoroughly. One man and a 2-horse team with this machine 

 could cover 35 acres per day at a total cost for labor and material of 



