December, '19] illingworth: white grubs and sugar cane 451 



INVESTIGATION OF CONTROL MEASURES FOR WHITE GRUBS 

 AFFECTING SUGAR CANE IN QUEENSLAND 



By J. F. Illingworth, Gordonvale, near Cairns, North Queensland 



After two years of this investigation I am more and more impressed 

 with the tremendous importance of the problem. Furthermore, I 

 appreciate that any successful methods of control should have a far- 

 reaching importance; for in many sugar-growing countries, as the 

 newer areas are opened up, these insects appear to be on the increase. 



Investigation of control measures for white grubs injurious to field 

 crops is as old as Economic Entomology — more than thirty years ago 

 we find that these pests were a serious menace in Europe. When the 

 cockchafer appeared in Denmark in 1887 the government got behind 

 a movement for collecting the beetles by hand, which was carried out 

 so persistently and economically by the people that the country was 

 apparently quickly rid of the pest. Naturally similar»methods have 

 formerly been advocated for Queensland, and, in some localities vast 

 quantities of the beetles were collected, at great expense to the growers; 

 but with little apparent result. The only explanation that suggests 

 itself is that areas collected were comparatively small and the price 

 demanded for collecting would bankrupt a state, if all the beetles were 

 collected. These insects are indigenous on the wild grassland, which 

 is very extensive in North Queensland — much more so than the narrow 

 belts of cleared agricultural lands. It appears to me, something hke a 

 proposition of picking up all the insects on a square foot, in the middle 

 of a large field, then expecting that this small area would be freed of the 

 pest for succeeding crops. We get the same result — the beetles swarm 

 over it again from the surrounding infested lands, so that no noticeable 

 benefit appears. 



Damage Done by Grubs 



An estimation of the vast economic importance of this pest in Xorth 

 Queensland is difficult to formulate. First of all, wo should consider 

 the immense areas which have gone out of cultivation, solely because 

 of the grubs. On the friable red-volcanic soils, which arc of high 

 fertility, this is particularly true. Even mucli of the land that is now 

 planted to cane will soon go out, unless some relief is furnished. The 

 most distressing part of the situation is that the grubs wait until all 

 the work of planting, chipping and cultivation is tinislicd, and the cane 

 is laid by — all the expense has been put into it — when the grubs begin 

 their devastation. It is heartrending to view tlie ruin (mi an estate like 

 Greenhills in the Cairns district, where iuindreds of acres of beautiful, 



