On the Value of Poison Bait for Controlling 



Cane Qrubs. 



INTRODUCTORY. 



I'pox taking iij) the study of oui- most serious insect pest of .sugar-oaue. 

 the so-ealled Grey-baek Beetle (Lepidiota alhohirta, Water.), special 

 attention was naturally bestowed on the larval stage, which anmially 

 oecnpies a period of about six months. 



Control measures ai)plicabU" to this important i)liase of its life-cycle 

 were briefly discussed in a previous report (Aust. Sugar Journal, Vol. 

 YIl., p. 140). mention being made at the time of a dozen feasible methods 

 of procedure of more or less economic value arranged under the head- 

 ings — "Remedial,"' " Preventive," and " Natural Control." 



Before starting to fight a pest of this kind, a knowledge of its life- 

 history and economy is, of course, essential. 



In the present instance we have much to learn regarding the lial)its 

 of the gruli. but may, I think, assume its subterranean movements to be 

 aft'ected by various tropic influences other than those directly associated 

 Avith the act of nutrition or with climatic changes. 



Pr()l)ably every grower is familiar with at least two of the principal 

 actions of this pest, viz — (1) that of eating cane roots, and (2) of con- 

 tinually passing (piantities of soil through its body. These well-known 

 habits were thought to constitute a fitting basis on which to connnence 

 experimentation of a I'cmedial natur(\ a l)rief account of whicli will now 

 be given. 



Larvicides. 



Research work in this connection was .started in February, 1915. 

 when a number of insecticidal solutions were applied to cages containing 

 larvi-e of albohirta, with more or less satisfactory results (see Aust. 

 Sugar Journal, Vol. VIII., p. 62). The drawbacks to such a method of 

 control, however, were early realised, and the work abandoned in favour 

 of more liopeful measures. 



The question of poisoning the grub hy means of arsenicals, &c., 

 a])plied to the soil appearing worthy of investigation, a series of experi- 

 ments were undertaken along this line, tlie knowledge obtained being iu 

 .some instances of economic value. 



