MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 25 



pest, and that all standover cane in the district should be destroyed. 

 We certainly would emphasise the ploughing out of all standover cane, 

 for it acts as a breeding ground for all sorts of cane pests. 



The fact that allied bettles in America will not deposit their eggs 

 in fields covered with clover led us to experiment with Mauritius beans 

 as a cover crop here. We have not, however, found that this cover offers 

 a complete protection, for upon ploughing the beans under during January 

 a good many grubs turned up. The abundant humus-forming material 

 supplied by the green crop will, however, undoubtedly supply these 

 grubs, so that they will not do serious harm to the cane which has been 

 recently planted on the land. A possible explanation for the ovipositing 

 of the beetles in these plots is that there was a rather abundant scatter- 

 ing of Natal grass present, and this may have attracted the insects. 



Lepidiota frenchi in Virgin Soil. 



It is interesting to note the habit of this species in favouring uncul- 

 tivated areas for ovipositing. One can dig almost anywhere in blady- 

 grass at this season and find the grubs. Those of the present year 

 are now in the second stage, and rather small, while last year's grubs 

 are in the third or final stage, and are forming resting cells in which they 

 pupate, preparatory to emergence as beetles next December. The third- 

 stage grubs have practically finished their feeding now, but those of the 

 second stage will continue for another year, so it is unsafe to use grass 

 land immediately for cane if the small grubs are found very abundant 

 when ploughing. 



Notes on Lepidiota rothei. 



"In a recent report (January) mention was made of the occurrence 

 :at Meringa of the small cockchafer Lepidiota rothei, Blackburn, in 

 considerable numbers during December and part of January, Although 

 of minor importance as a cane pest, it was thought desirable at the time 

 to breed rothei from the egg, in order to determine the duration of its 

 life cycle. This insect emerges about the same time as frenchi, from 

 which, however, it differs in being decidedly smaller and of darker 

 colouration. The following brief allusion to the earlier stages of its life 

 cycle may be of interest : — 



"The eggs are laid from seven to twelve days after copulation, the 

 numbers obtained from individual females confined in cages varying 

 from four to twelve. Like those of frenchi, which they resemble in 

 general appearance, these eggs, although placed close together, are not 

 massed in a single large chamber, but deposited separately, each egg 

 Tjeing isolated in a tiny cavity. An interval of from nine to eleven 

 days elapses between the acts of oviposition and emergence of the young 

 grubs, while the first larval stage occupies a period of about ten weeks. 

 'This, however, may vary considerably, as in some instances grubs 



