THE PESTS AD DISEASES OF THE CANE. 



For a detailed study of the control of insect pest by insect parasite 

 reference may be made to the detailed account of the leaf hopper in the 

 entomological bulletins of the Hawaiian Sugar Planters' Association. 



Froggat 17 however, has very severely criticised the pest control work of 

 Koebele and Perkins, and is inclined to attribute the diminution of the leaf 

 hopper to the burning of trash, (a custom which had been in vogue for a 

 generation previous to the appearance of the hopper), and which Perkins 

 indeed does not advise since the hopper can escape by flight, whilst the 

 parasites are unable to do so. A change in the variety of cane planted is also 

 given by Froggat as tending to have controlled the hopper, but although on 

 some plantations hard rinded varieties were hurriedly planted during the 

 first period of the epidemic, this alone had little effect, and plantations which 

 made no change obtained an effective control by means of parasitization. 



On the other hand, Silvestri, 18 who also studied the conditions locally, 

 writes in the highest terms of the work of Koebele and Perkins, and considers 

 that there is no doubt of the economic success of insect pest control through 

 the agency of their parasites. 



Insect Epidemics. In the preceding pages reference has been made 

 to several historic insect epidemics ; in many of these there is strong evidence 

 that the epidemic was due to external introductions and these may then be 

 classed as instances of the disturbance of the natural balance. In one instance, 

 at least, an epidemic was probably due to wilful neglect of warning and to 

 disobedience of State orders. The losses suffered by Mauritian planters, about 

 1850, from the borer should be sufficient to warrant the introduction of new 

 varieties of cane only under a well advised system of inspection and quarantine 



Insect epidemics may however arise from uncontrollable causes, as 

 instanced by the present (1910) serious aspect of the spread of the Giant 

 Borer (Castnia licus] in British Guiana 19 . This insect was first noticed as 

 casually attacking cane about 1901 on the East Coast of Demerara ; in 1904, 

 it was reported as doing great damage to cane at ' Enmore ' in that district ; 

 previously its food habits were only connected with the roots of an orchid 

 growing near the Upper Orinoco. As this insect is known from Central 

 America to the Amazon, it probably was not a recent introduction, but 

 suddenly for obscure reasons developed the faculty of feeding on the cane. 



Although the presence of an active State entomologist would not have 

 influenced the development of the habits of this insect, yet the reporting to 

 such an official of the first observed damage in 1901 would have allowed him 

 time to study its life history, to have warned planters of the imminent 

 danger, and to have devised means for its control. 



In any community dependent on agriculture for its prosperity, a depart- 

 ment of economic entomology is necessary ; the losses due to preventable 

 epidemics would pay the expenses many times over ; whether the officials of 

 such a body should be the servants of the State or employes of a private 



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