MONTHLY NOTES ON GEUBS AND OTHEE CANE PESTS. II 



CANE GRUB INVESTIGATION, DECEMBER, 1917. 



The primary emergence of grey-back beetles took place earlier than 

 usual this season, about the end of October, and specimens placed in 

 the Inseetary on 9th November deposited eggs from which grubs 

 hatched out during the first week in December. 



Another emergence of this beetle occurred about 3rd December^ 

 and owing to the prolonged showery weather egg-laden female speci- 

 mens are still much in evidence (14th December). 



Unless we have a considerable emergence later on, this year's tiight 

 will be far below the average. Though emergence has been spread over 

 a period longer than usual, comparatively few beetles have been on the 

 trees at any one time. 



Emergence op Lepidiota Frenchi and Rothei. 



In the region immediately around Meringa, both frenchi and rothei 

 are much more in evidence than the regular cane beetle, L. albohirta-. 

 These two smaller species began to emerge about the 1st of December, 

 and (14th December) they are still abundant on the feeding trees and 

 low shrubs, fences, grass, &c., where they are mating. These beetles 

 emerge earlier in the evening than the grey-backs, and they are easier 

 to collect because they mate on lower objects, and can easily be picked 

 off by hand. Often half a dozen pairs are clustered near together, so 

 that they can all be taken in one hand. 



Although the usual biennial occurrence of frenclii does not take 

 place until next year, small local emergences are generally noticed each 

 season. At present the grubs of frenchi are nearly full-grown, and doing 

 great damage in places to both ratoon and young plant cane in the 

 region about Gordonvale. This damage results in a peculiar spotted ap- 

 pearance of the field, for here and there, a chain or so in extent, the 

 cane is j^ellow and often dead, while the surrounding cane is dark- 

 green and thrifty. In one field of plant cane at Meringa, fully one-third 

 of the crop is damaged in this way. The land had not been in cane for 

 some time, and w^as covered with a heavy growth of burr and grass. 

 The soil was thoroughly worked previous to planting cane ; and though 

 many small grubs were noticed when ploughing last May, no attention 

 was given to destroying them. These grubs were evidently the younger 

 stages of frenchi, which now, in their third stage, are able to do such 

 serious damage to the roots. 



"By giving attention to the advice tendered by this Office in the 

 monthly report for last May ('Australian Sugar Journal,' IX., p. 221), 

 growers will probably be relieved of considerable future damage from 

 these pests. 



