32 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 
Mr. Ernest S. Smith, cane inspector at Goondi Mill, from his exten- 
sive observations in the district, 1s emphatic in his belief that the 
proximity of the feeding-trees accounts for grubs in the soil. He told 
me that it is a well-recognised fact that grubs which were once very 
serious throughout the Goondi district have disappeared as the line of 
serub has been moved back. It is now only the land lying within half a 
mile of the serub which is affected. He could not recall a single instance 
where fields farther away from the feeding-trees were troubled. 
That it is not the length of time that land has been cleared which 
makes it immune, Mr. Smith cited the Innisfail Estate, which was 
opened up about thirty years ago, and is still troubled badly with grubs 
every year, simply because it is bordered by serub, for the same class of 
land on the town side of the river is not infested. 
In October, 1917, I called attention to an interesting observation 
in connection with this subject by Mr. W. Walker, who has been a resi- 
dent of Macknade district for the past forty years. Mr. Walker used to 
notice a very definite relation of infestation to a particular fig tree in his 
fields. He found that the beetles usually went from this feeding-tree 
with the wind, and infested the cane on that side, at some distance from 
the tree more than immediately around it. 
This suggestion bears fruit when we study an estate like Greenhills, 
where there is always a considerable portion infested. For two seasons 
I have been collecting data as to the distribution of the grubby areas, 
and have indicated these upon a carefully-drawn map, using degrees of 
shading to show relative abundance. 
Examination of this map points clearly to the fact that the infested 
fields lie large within one-half mile of the feeding-trees, and also that 
the prevailing winds from the south-east are largely responsible for 
bringing the beetles from the feeding-trees, which are abundant in that 
direction. Attention should be called to the fact that there is a con- 
siderable area of the estate which is considered land safe from infesta- 
tion, and though part of, this is bordered by the forest to the west, the 
eane is but little infested, evidently because the prevailing winds blow 
away from these fields into the feeding-trees. 
It must be kept in mind that cane is not at all essential to the beetles 
in their development, for they thrive just as well in grass land; in fact, 
the wild grasses are the beetles’ native food-plants. It is interesting to 
note, in this connection, that the grey-backs are very abundant, even up 
on top of the range, where there is no sugarcane for them to feed upon. 
The only reason that they become such a pest in some of our fields is that 
we have subjected them to abnormal conditions, by removing their native 
food plants and destroying all humus in the soil by our destructive 
methods of farming, by taking off the crop every year, and even burning 
all the trash. 
Careful measurements in the region about Meringa, where the cane 
has suffered severely from grubs for years, show that all the infested 
