6 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 
Our laboratory experiments of placing megass in the soil of potted 
cane plants proved very encouraging; for the grubs quickly destroyed 
the roots of the plants in the check pots (those containing no megass), 
while in the ones under treatment the grubs fed upon this organic 
material in preference to eating the roots of the growing cane. Dr. J. 
H. Reed tells me that he tried a similar experiment, with the same 
result, the only difference being that he used chop-chop to mix with the 
soil. 
Everyone who has had anything to do with the growing of cane on 
infested land has probably noticed that some of the stools at the ends 
of the rows are of more sturdy growth, and that these stools often keep 
their footing when the balance of the field goes down. This matter 
has been variously explained by growers, some contending that the 
increased growth may be accounted for by the fact that these stools are 
less crowded. If this was the correct explanation, we would naturally 
expect to find the same increased growth along the, sides of the field, 
which does not usually appear. My explanation, borne out by experi- 
mentation, is that there is more humus-forming material in these par- 
ticular spots, for in working the land the thrash is naturally dragged 
to the ends, where it eventually becomes broken up and mixed with the 
soil. 
Again, it appears to be rather common experience that grubs are 
not so bad on land after it has been thrown out of cultivation for three 
or four years. I believe this may be explained, also, on the grounds of 
accumulated humus; for, usually, the weeds and trash are allowed to 
remain while the land is idle, and are eventually worked into the soil. 
On the other hand, the immunity of cane planted on particularly 
rich land, such as river flats, is evidently due to the fact that soils 
subject to occasional overflow are naturally rich in organic matter. 
Nevertheless, even these soils can be quickly ruined by continual 
croppings, combined with the burning of all trash. In such cases the 
appearance of grubs on the cane is an almost sure indication that the 
ground requires more humus. An instance of this kind has been under 
investigation during the past month. The field, lying on the river bank, 
has a soil of great depth, and has been planted with sugar-cane for years. 
I am told that as long as eight years ago the grubs were found in great 
numbers under the stools, yet the cane showed no injury. The soil being 
evidently rich enough to feed them, the grubs were not forced to resort 
to the living cane roots for subsistence. During the past season, however, 
the cane in this field suffered severely, and investigation shows that there 
are as many grubs in this soil as in our worst districts. Destruction of 
the roots by grubs, combined with the cyclone, put all the cane down, 
which is therefore badly deteriorated. 
I realise that the conserving of trash on red voleanic soils is a 
difficult matter, especially with our present implements; but it must be 
done, unless a great deal of time is devoted to green manuring. On soils 
that will scour, however, there is little excuse for the destruction of all 
