MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 35 
matter to destroy all of them by horse-work, for they are probably placed 
near, or under, the stool. The fields which received this cultivation are 
in excellent condition at present (14th March), and have a fine dark 
colour. The field J1 is a good example, since it has suffered from the 
grubs in former years. It is worth noting that this field was planted 
very late last October, for J4, which was planted in August, is suffering 
severely from grubs, and is located just across the tramline, and more 
distant from the feeding-trees. 
In support of this contention I might mention the two ratoon fields, 
L7 and the lower half of L6, which were cut in November and ratooned 
while the beetles were on the wing. Both fields are in prime condition, 
with no apparent signs of grubs, while several of the fields nearby are 
already going yellow. It will be recalled that these fields were planted in 
October, 1917, and gave successful cuts last season. 
ON THE VALUE OF GREEN CROPS. 
The finest cane on the Greenhills Estate is in the part of F3 which 
was planted with Mauritius beans. The lower part of this block was not 
treated, and it 1s easy to see where the beans ended, for there the cane 
is shorter and is badly yellowing from an attack of grubs. All of this 
block was a failure last time it was planted. 
: MeERINGA EXPERIMENTAL PLOTS. 
The cane in these plots is in excellent condition, especially the areas 
which were under beans. All of the fifteen plots, which include the 
checks, have had frequent cultivation during the whole flight of the 
beetles, and this probably had considerably reduced the number of grubs. 
While it is rather early to draw conclusions, I would say, from tests 
that we have made of individual stools in the various plots, that white 
arsenic gives considerable promise when used in the drill at the time of 
planting, especially when mixed with meatworks manure, which the grubs 
appear to favour as food. 
CARBON BISULPHIDE EXPERIMENTS. 
The following observations were made on a badly infested field (B1 
of Gordonvale farm) of first ratoons. By digging test stools early in 
February, while the cane was still of good colour, I found that the 
number of grubs ran from 8 to 49. The owner decided to apply carbon 
bisulphide, and this was started on the 18th of February. The applica- 
tion was made with the ordinary Danks pump, set so that the discharge 
was about 3 inches beneath the surface. The maximum charge was given 
(slot No. 91 drachm and 55 minims) on one side of the stool, to start 
with, but the middle of the field was treated on both sides of the stool, 
using the same charge. Finally, the last part of the field was not treated, 
for heavy rains (about 10 inches) started on the 25th of February. 
On 8th March I examined this field for grubs, and found excellent 
