166 E. A. TEMPANY AND D. d'eMMEHEZ DE CHARMOY. 



The measures above indicated liave on the whole provided adequate machinery 

 for the control of the pest. One point, however, requires mention, namely the risk 

 of artificial dissemination of the pest by interested parties, as a result of the policy 

 of buying the beetles. To guard against this a supplementary Ordinance was passed 

 in 1918, whereby any person wilfully disseminating a plant disease is rendered 

 liable to imprisonment without the option of a fine. 



Other Methods of Control. 



In the early days of the outbreak, a considerable number of experiments were 

 tried on methods of control, other than those enumerated above. These included 

 the trial of various stomach and contact poisons and also the injection of carbon 

 bisulphide and other poisons into the soil. The pest, however, exists in such numbers 

 and on such very extensive areas that the cost of methods of this description renders 

 their employment prohibitive for the most part. The principal methods which 

 have been tried are described below. 



Numerous experiments were undertaken at the outset with a view to finding an 

 efiicient insecticide, moderate in cost and easily apphcable, that would permit of 

 the control of the pest, more particularly on young plantations, as these suffered most 

 from its attacks. 



Powder insecticides, such as Paris green and vaporite, proved unsuitable on 

 account of the labour expenses involved in their application. Neither potassium 

 cyanide nor carbon bisulphide could be utilised, not only on account of the expense, 

 but owing also to their harmful efiects on plants. Liquid insecticides, involving 

 the use of kerosene, creohne and carbohc acid, though rather expensive, gave more 

 satisfactory results when deahng with young plantations and first ratoons, but tlieir 

 apph cation could not be generalised, in most cases for want of the water needed in 

 their preparation. 



Experiments were also tried with the object of finding some substance that would 

 attract the larvae. Good results were obtained with refuse cane-cuttings and tops. 

 These were spHt in halves and buried in smaU furrows 2 or 3 inches deep. Every 

 fortnight the furrows were opened, the cuttings turned over and the larvae removed, 

 the same cuttings being replaced and revisited. This method not only aUows of 

 the destruction of the pest at a comparatively cheap rate, but also prevents the 

 larvae from entering the planting holes when in search of food. 



Other substances such as molasses, ashes, scums, &c,, have been experimented 

 with, but without success ; attempts were in addition made to infect adults and larvae 

 with cryptogamic diseases. Those affecting larvae proved contagious, but could 

 not be transmitted experimentally ; while the one that attacks the beetle and was 

 introduced from Porto Eico {Metarrhizium anisopliae) gave poor results. It was 

 found subsequently that this fungus existed already in the Colony, attacking various 

 species of Scarabaeidae, but did not exert any very great influence in checking 

 their spread. 



The Number of Insects captured and the Results of the Campaign. 



The statistics for the number of insects captured afford the best indications of 

 the total prevalence of the pest. These are given below in tabular form, the figures 

 showing both insects and larvae destroyed on all the properties concerned. 



