152 



CHAPTER IX 



that by means of systematic collection over three years the pest nearly 

 disappeared. Similarly, S. M. Hadi^^ has recorded that in India the white ant 

 is attracted by dung, which is purposely placed on the canefields. 



3. Rotation of Crops. — This is recommended by Watson as likely to 

 diminish the prevalence of the root borer, Diaprepes abbreviatus, and 

 amongst crops not attacked he mentions ochra, yams, eddoes, woolly 

 pyrrol, pigeon pea, bonavist bean, and rouncival beans. 



4. Use of Insecticide Washes.— The great area of plantations prevents 

 the utilization of this means, which is necessarily confined to orchards and 

 similar industries where the crop is produced under intensive rather than 

 under extensive conditions. 



5. Flooding. — The flooding of fields has been used to destroy such 

 insects as are of subterranean habit in part of their existence, such as the 

 *' large " moth borer, Castnia licus. 



6. Destruction of Breeding Places. — Whenever possible this method is 

 f.ne of great effectiveness, and it is applied on an extensive scale in the 



Fig. 45 



campaigns carried out against the mosquito and other disease carriers. 

 In the Hawaiian Islands, also, systematic measures are taken to destroy the 

 eggs of the sarcophagid flies which breed in latrines, and which are associated 

 with the spread of typhoid and other intestinal diseases. While not directly 

 connected with growing cane, attention to such matters has an important 

 economic bearing as affecting the health and efficiency of the population of an 

 estate. 



In regard to sugar cane insects, the matter is complicated by a number of 

 factors. Guilding,!! whose remarks are quoted below, in 1834 advised 

 trashing as a means of reducing the numbers of the moth borer, but other 

 factors have to be considered, and often the limited labour supply will prevent 

 anything of this nature. 



Uncontrollable local conditions may also be a factor aiding the unre- 

 stricted development of a pest. Such a condition is discussed by Walcott^e 

 as obtaining in British Guiana, where, owing to climatic conditions, cane 

 in all stages of growth is to be found in juxtaposition. There is thus a 

 constant habitat of young cane, which is preferred by the borer for ovi- 

 positing. Quelch^^ has made suggestion that this state of affairs might be 

 remedied b>' planting areas of large units separated by distances greater 

 than the normal range of flight of the borer. 



