26 MONTHLY NOTES OX GRUBS AND OTHER CANE PESTS. 



remained four months or longer in the first stage ; and in one case, for- 

 example, we found first, second, and third-stage larva? derived from eggs/ 

 hatched together, and living under precisely similar conditions in respect 

 to temperature, moisture, and food supply. The interval from second 

 to third instars is about six weeks, and third-stage larvjB were obtained 

 from our breeding cages by 28th April. 



Notes on Lepidiota xVLbohirta. 

 ' ' Investigations conducted at Meringa on volcanic land suffering from 

 severe grub attack revealed the fad that 10 per cent, of the grubs after 

 having eaten every root were actively devouring the last few inches of 

 stalk still attached to the old sets, the remnant of cane that had been 

 previously bitten off level with the ground. These pieces of stalk were 

 hollowed out and reduced to shell-like fragments, even the hard outside 

 rind being eaten, which would seem to indicate that instead of travelling 

 in search of fresh succulent cane roots the grubs are content to continue 

 feeding on such vegetable tissue as may be readily available even though 

 less palatable. 



"The remaining 90 per cent, of larva^ unearthed on this occasion had 

 formed cells in the hard soil preparatory to pupating, 70 per cent, of 

 these being found at depths varying from 11 to 18 inches." 



CANE GRUB INVESTIGATION, JUNE, 1918. 

 During the month I made a general survey of the Northern sugar- 

 growing districts, extending as far south as Innisfail. The trip was a 

 very interesting and profitable one. for it not only gave us a line upon 

 the distribution of our principal pests of sugar-cane and the discovery 

 of a valuable parasite, but, most important of all, is the acquaintance with 

 the men who are the leaders of the industry in these districts. 



Babinda District, 



This whole section suffered rather severely in the March cyclone, 

 so that it is rather difficult to say from a casual observation which fields 

 are grub-infested and which are down only because of the wind. The 

 grubs have mostly gone down, preparatory to pupation; but if present 

 in the field we were always able to locate thera in their pupation cells. 

 To do this it was necessary to dig pits at least 3 feet deep — the maximum 

 depth at which we have found the grubs, though the average depth for 

 pupation is only about 2 feet. 



Though there is evidence that the grubs of the common grey-backed 

 beetle extend along the line from Gordonvale to Babinda, certainly the 

 worst infestation is in the region about Fishery Creek. As in other 

 locations, the grubs here bother the cane only on the higher ground, 

 away from the river. The newly-cleared scrub on this ground is only 



