Notes on Insects Damaging Sugar Cane in Queensland. 37 



Control specimens, 30 in all, feeding on unsprayed leaves lived for 

 fourteen days, and did not eat more food proportionately than beetles 

 confined with poisoned foliage. 



Barium chloride 2 per cent, solution (6 lb. to 30 gallons water) 

 gave negative results, and apparently made foliage distasteful. 



Deterrents for Cane-gruhs. 



An account of initial experiments carried out for the purpose of 

 determining the deterrent qualities of dichlorbenzole was published in 

 April, 1915 (Australian Sugar Journal, vol. 7, p. 214). Land treated 

 with 1/4-oz. injections became after nine days sufficiently impregnated 

 to drive away or kill all grubs located within a distance of 8 inches 

 from the chemical. In dry weather a quarter of an ounce, after being 

 fifteen days underground at a depth of 7 inches, subjected to an average 

 temperature of 69 degrees Fahr., weighed 3 scruples 5 grains, thus indi- 

 cating a loss of nearly 50 per cent., but did not actually disappear until 

 the end of six weeks. Better results could, doubtless, be obtained from 

 injections made of a single lump, like a " moth-ball," as in this form 

 the same amount of chemical might last two months or longer. Under 

 wet conditions both evaporation and soil infection were retarded. 



It is worth noting, however, that the deterrent odour remains in the 

 ground long after all traces of its origin have vanished. Soil under 

 cane stools treated 5th March was found to be strongly infected on the 

 8th of j\Iay, three weeks after complete evaporation, from which we may 

 reasonably assume that a limited area of such contaminated soil — com- 

 prising, say, a strip at least a foot wide — would continue repellent until 

 the odour became less decided. 



(41) LEPIDIOTA FRENCHI, Blackb. (Family MELOLONTHIDAE). 

 Plate IV., Fig. 41, p. 34. 



This widely distributed and very abundant insect breeds in unbroken 

 forest land but is frequently found in canefields and is at times respon- 

 sible for considerable damage. 



Some idea of its excessive numbers may be gathered from the fact 

 that last January (1915) four collectors in half an hour picked off no 

 less than 10,925 of these beetles from the fence of Gordonvale Recreation 

 Reserve, in the centre of the township. 



A thick growth of weeds is likely to induce attack and should never 

 be allowed to occupy plantations or land intended for cane during the 

 period when this species is ovipositing. 



Description of Beetle. 

 Dull whitish-red, finely and rather closely punctate on dorsal sur- 

 face, each puncture containing a single white, nearly circular scale. 

 Sides of prothorax acute Avith edge dark red, turned up nnd synimetrieally 



