GREYBACK CAXE BEETLE, LEPIDODEEMA ALBOHIETUM. 11 



speaking on the subject of an entomologist for the sugar industiy, 

 remarked that during the season of 1910-11 over £3,000 was spent in the 

 eradication of grubs in the Cairns district. They had destroyed 22 tons 

 of beetles and 9 tons of grubs. It was estimated that there was an annual 

 loss of 25,000 to 30.000 tons of cane in that one district. And, later, 

 while on a deputation to the ]Minister for Agriculture in 1912, Mr. 

 Pritchard (53) estimated that the annual losses from grubs on cane in 

 i^ueensland were fully £100,000. 



NATURE OF THE INJURY. 



Grubs are most destructive on well-drained land; consec^uently, in 

 Northern Queensland, crops on the red volcanic soils are usually the 

 Avorst aifected. These soils are very porous, often extending to a great 

 depth, and underlaid with gravelly subsoils. As a matter of fact, they 

 are so friable that they may be cultivated at almost any time, even during 

 the rainy season when it Avould be disastrous to go on to the tields of 

 heavier clay. Then, too, because of the loose nature of the red soils, 

 especially in districts with heavy rainfalls, they are usually poor in both 

 humus and lime, which, we shall see later, are of considerable importance 

 for the growing of successful crops. 



As is Avell known, the grubs of the greyback beetle, Lepidodernia 

 ■aJhohiiium — the principal cane-pest of Northern Queensland — are only 

 destructive during a few months out of the year, from about February 

 to May. During this time, however, they attack sugar-cane in any stage 

 •of its growth. 



Ordinarily the cane is well advanced at this season, but it makes 

 little difference in Avhat stage it is. for as soon as the Aveather turns 

 dry the leaA'es begin to yellow and wither a,s if suffering from extreme 

 drought. In badly aft'eeted areas, like the Greenhills estate, this is a 

 most heartrending sight, especially Avhen one considers all the effort that 

 has gone into the crop ; yet, year after year, hundreds of acres succumb 

 in this Avay on the above estate, the leaA'es finally becoming as dry a,s if 

 a fire had been through the fields. This drought-stricken appearance is 

 due to the fact that the roots have all been eaten oft' and often the root- 

 stocks, too, badly gnawed, so that one can easily pull the stools right out 

 of the ground. In fact, I have sometimes seen the cutters jerk out the 

 individual stalks, Avhen harvesting grubby cane, because it was easier 

 than cutting them off'. Of course, under such conditions the ratoons are 

 worthless, but in any case they are likely to be after such devastation by 

 the grubs. 



Furthermore, in the case of mature cane the damage often occurs 

 .several months l^efore the mills open up for crushing, and there is 

 inevitably considerable loss through deterioration, for the lateral eyes on 

 :grul)by cane grow out at the expense of the sugar content. Nevertheless, 

 if there is no wind this cane does not usually fall down, and a partial 

 return is secured from the crop. On the other hand, Avith a cyclone such 

 as that of 10th March, 1918, or the one of 2nd February, 1920, all of the 

 mature cane that has been badly injured by grubs is tipped right out of 

 •the ground, and many thousands of tons rot before it can be milled. 



With late-planted (i.e. September-October) cane, the procedure is 

 somewhat ditt'erent, for the crop usually grows Avell until about February, 

 when it is ready to "lay by," then suddenly, if there are many 

 grubs present in the soil, it ceases to develop, and the leaves soon have 



