94 AFSTEALIAX SUGAR-CANE BEETLES AND THEIR ALLIES. 



Again, since meatworks manure is evidently attractive to grubs, it 

 is probably only a matter of finding how nivich poison to use with this 

 fertiliser to get results. It will be recalled that Mr. C. E. La Caze 

 reported successful control after an application of 70 lb. of arsenic per 

 acre, though there may have been other factors entering into his results, 

 since he kept no check-plots. At any rate, this is a suggestive line of 

 control, which is particularly easy of application, since it tits splendidly 

 into ordinary field practice. The amounts of arsenic should be varied, 

 for experiment, to learn how nuich of the poison is required for results. 

 I would suggest using 80 lb., 100 lb., 150 lb., and 200 11). This could 

 best be mixed during the manufacture of the manure, thus avoiding the 

 handling of the poison by inexperienced men. Applying the fertiliser 

 with the ordinary manure spreader, it will be best to keep the delivery 

 pipes near the roots of the cane, for with ordinary conditions the grubs 

 remain close under the stools. ^Moreover, our experiments have shown 

 that for best results the poison must not be placed too deep in the soil : 

 so it will probably be best to make the application after the drills are 

 partly filled in by cultivation. 



Then, too, further experiments should be tried with poisons for 

 the destruction of the beetles, especially the greybacks; for, since they 

 are such voracious feeders, there is a possibility of success. A few of 

 their favourite feeding-trees could he treated for a test. I would suggest 

 dusting experiments as Avell as spraying, and a trying-out of calcium 

 arsenate, ccnnparing it with the lead arsenate. Both of these poisons, 

 may now be had in the powdered form ; so dusting, being more economical, 

 has come much into vogue for the control of leaf-eating pests. 



In l^uUetin No. 12 I have recommended the further introduction 

 of friendly organisms. The experience of Hawaii, however, teaches that 

 that work must be entered into wholeheartedly for a successful outcome. 

 It requires years of the most strenuous work, but the final results must 

 certainly pay. A well-trained field entomologist should be despatched 

 as soon as possible, and given a free hand for at least five years. NeAv 

 Guinea. Java, and the Philippine Islands will probably prove the richest 

 locations for this investigation. 



