QUEENSLAND.

_ BUREAU OF SUGAR EXPERIMENT STATIONS.

DIVISION OF ENTOMOLOGY.
BULLETIN No. 8

S Monthly Notes on Grubs and other
2 Cane Pests. —

(SECOND SERIES.)

NN LE SR SNA TS ESTOS SOU SE TT a

J. F. ILLINGWORTH. _

1918-1919.

Anthony James Cumming, Government

SEE pe

QUEENSLAND.

BUREAU OF SUGAR EXPERIMENT STATIONS.

DIVISION OF ENTOMOLOGY.
BULLETIN No. 8.

Monthly Notes on Grubs and other
Cane Pests

(SECOND SERIES).

J. F. ILLINGWORTH.

1918-1919.

BRISBANE:
By Authority: Anthony James Cumming, Government Printer.

<1 a7
cu ma

Die AP DD ee ed

a

SU op nS,

ee Ma)
ey CAN Wa a
r » 4 iiszy LT
Ph fe 4’
Be i Say ee “
nae at aye 8 v

ia a
iid
|

urs
J
Pare

Bureau of Sugar Experiment Stations,
Brisbane, 15th October, 1919.
The Under Secretary,

Department of Agriculture,
Brisbane.

Sir,—I have the honour to submit for publication as Bulletin No. 8
of the Division of Entomology of the Bureau of Sugar Experiment Sta-
tions a second series of Monthly Notes on the Grub and Other Cane
Pests, by Dr. J. F. Illingworth.

I have the honour to be, sir,
Your obedient servant,

HARRY T. EASTERBY, General Superintendent.
Approved:
EK. G. BE. Scriven,
Under Secretary.

hoi hs Sto

. Paw

Pe ae oe *:

Oe bee ee ee
r c

; i seat i Pies a on ae ite mr q
ais eine, aa ‘gek: jaa nag Felt he 4
a eet ne eae, es a 4
Wa a Mary hal n

: eae

a Le -
i KY a oc hath “ai tr a

' i : 4

ones r ve pak wit ee

| | ba (ant ag
Mae A? eek ‘1 aad, ee

5) os

es:
Og) Ree. iy

. ;

Bsa er! ware . F

aww o

.

e.-
7.
. ¢
oe
a.
2 ®
es
oS
zs
a:
aglGe

SKETCH OF GREENHILLS ESTATE.

Grub infestation indicated by Degree of Shading. White, immune area.
Arrows show direction of prevailing wincls.
+++ = Feeding trees of the Beetles.
= Roads and Headlands.
++-++4+-+ Tramlines. [Pace Page 5.)

Monthly Notes on Grubs and other Cane Pests.

By J. F. ILLInewortuH.

CANE GRUB INVESTIGATION, JULY, 1918.

I have been greatly interested in the rather general acceptance of
the idea of late planting for infested soils. Almost everywhere we go
we find the farmers routing out the grubby fields; and a number
have told me that it is their intention to work the ground thoroughly,
preparatory to late planting. There is certainly no time like the present
for killing weeds; and if the soil is kept clean-fallow until September,
the cane should require very little chipping, thus removing one of the
great objections to late planting, 7.e¢., the difficulty of keeping the crop
clean during the wet weather. Let me repeat, then, and urge that all
infested soils, especially the red volcanic, be thoroughly worked and
kept in clean-fallow until planted in September or October. During
the process of ploughing three or four times it is possible to work a
great deal of trash and other organic matter into the soil; this is worth
all the extra effort required to conserve this humus-forming material,
for, as explained further on, it undoubtedly is a vital factor in grub
control. °

Let me again call attention to a very interesting experiment at
Greenhills, where in one field (L6) half of the cane was planted in June,
1917, and the rest in October. The latter half is now beautiful cane,
very erect and green, in marked contrast to the early-planted half, which
went down in the cyclone after a bad attack of grubs. Furthermore,
this early cane has deteriorated so much that it is very doubtful if any
of it will be fit for milling. This field is particularly interesting because
the two plantings are side by side, having the same care, and exactly
the same soil.

ON THE VALUE OF ORGANIC MATTER IN THE SOIL.

Early in experimentation, from our knowledge of the feeding habits
of the grubs, I was convinced of the value of humus-forming material
‘as a factor in their control. Hence, we have followed the matter up
with increasing interest.

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

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 7

trash. The waste from the ratoon crop should be worked in, and this
followed with a heavy green crop of corn or beans to put the soil in
prime condition for a new run of cane. If this regular rotation is
followed up, the land will not deteriorate; and I feel rather confident
that there will be a marked decrease in the injury from the grubs.

A Stupy or THE Rootinc SYSTEMS OF OUR PRINCIPAL SUGARCANES.

We have been making some investigation of the rooting systems,
particularly in regard to depth, with the idea in mind that if we could
get a variety which would root more deeply than Badila it would be
more apt to stand up when attacked by grubs. We naturally looked
to D1135, since this cane ratoons so well and has an erect growth. It
is also the variety grown largely at Mossman, and is considered rather
resistant to the attacks of grubs. Digging in the stools, we found that
the principal roots of this cane extended downward, often to a depth
of 16 or 18 inches, which is in marked contrast to Goru, with most of its
roots extending laterally, often reaching across to the next row. D1135
is a good milling cane, with plenty of fibre, and, even though it is of
only average density, will be a valuable variety to grow if it can be
shown that it is grub-resistant. There are several fields of this variety
in the grub-infested region about Meringa, which so far are in very
good condition.

Notes ON LEPIDIOTA ALBOHIRTA.

It is interesting to note that the beetles are very early in forming
this season. We have been finding them, turned up by the plough,
during the past several weeks. Apparently, many of the grubs pupated
near the surface this season, so that many of them are uncovered or
erushed in ploughing. Fully three-fourths of those observed were
injured in this way, which seems to indicate that working the ground
at this season, or earlier, was a profitable procedure.

In following the plough it is very noticeable that all the grubs present
in the upper 10 inches of soil are under the old stools of cane, and that
many are eating right into the old stalks.

In digging in a patch of blady grass, while searching for frencht
grubs, I was surprised to find many of this common grey-back species.
They were all in pupating c¢ells, from 1 to 2 feet deep. Such finds would
indicate that we shall always have the beetles with us, for these native
breeding-places can never be entirely done away with.

Notes oN LEPIDIOTA FRENCHI.

This troublesome species is also a native of grass lands; but it is
particularly inimical to sugarcane, because it lasts over for two seasons.
The grubs, which were fully grown and feeding on the young plant cane
last November, had not yet changed to pup on the Ist of July, though

8 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

they were found in well-formed cells about 2 feet below the surface.
The inner lining of the cell was evidently made from the excrement of
the body, which had been formed into a smooth, hard layer.

The second-stage grubs are still much in evidence when following
the plough on new land. In this stage the grubs are still small, but will
be grown up by October, and ready to do considerable damage wherever
they occur.

PARASITES AT HAMBLEDON.

This district was once a grub centre, and it has been an important
question as to what their disappearance could be attributed to. As far
as I could learn, there has been no change in cultural methods—no removal
of feeding-trees, or other treatment applied. Of course, vigorous
methods were applied at the time, in endeavours to rid the place of the
pest, but these same methods, tried in other sections, have failed. Tryon
suggested, in his valuable ‘‘Bulletin on the Grub Pest of Sugar-cane,’’
that one or more of the natural enemies might be at work in this district.
It was therefore with considerable interest that I made the discovery
that this surmise was correct. The fields are plentifully supplied with
the Campsomeris wasps, which are seen flying about everywhere. By
digging pits we found that the cocoons of the wasps were abundant
under the stools, and that a fair number of grubs were present. The
cane showed no injury, except what might have resulted from the cyclone.

The activity of these wasps in the laboratory shows that they would
make short work of the grubs, if they could in their turn escape from
their own natural enemies.

4

OTHER GRUB DESTROYERS.

It is a revelation to follow the plough during July, and note the
cleaning up of the grubs by birds. In one field at Meringa, fully 150
ibises were following two ploughs, leaving not a single grub in their wake.
The birds were spread out the whole length of the furrow, which was
about 15 chains long, so that their keen eyes detected everything. By
following close to the plough we saw that many grubs were turned out
from under the stools, but, as soon as the birds had passed along, not one
remained. The appetites of these birds is marvellous, for they follow
the ploughs assiduously all day long. The contents of their stomachs
have been examined when grasshoppers were abundant, and no less than
2,000 young locusts were found in a single bird. These birds are certainly
valuable allies of the farmer, and it is a fine thing that they are pro-
tected. They are, however, still very timid, showing that they are subject
to more or less injury by ruthless humans.

The pewee larks, too, do a lot of good work behind the ploughs,
though these birds are not large enough to swallow the largest grubs.
[ have often watched them break up the biggest grubs before they tried
to swallow them.

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 9

We need further observations on the bandicoot, which is undoubtedly
a great destroyer of insect pests. We have, in former reports, called
attention to the useful habits of this animal, but it will be interesting
to record a specimen recently dissected by Mr. Girault. Though the
animal, which was fully grown, had been killed some time before by
dogs, it was possible to remove the alimentary canal almost intact. Mr.
Girault’s notes state that the following remarkable contents of the
stomach were easily identified :—1 unknown Scarabeid grub; 30 slender,
pale caterpillars, of the same species, and about 14 inch long; frag-
ments of 2 moderate-sized beetles; 1 oat-like seed; 2 large Chrysomelid
beetles; 2 large ants; 1 large unknown beetle; fragments of a longicorn
beetle ; cane leaf, pith, and about 3 ec. of dark-green matter, composed of
mixed insect and vegetable remains, these latter accounted for by the
eaterpillars, perhaps.

CANE GRUB INVESTIGATION, AUGUST, 1918.

During the month I made a second trip to the Mossman district,
this time to obtain a supply of the tachinid parasite of the borer weevil.
Though my stay was very brief, I was able to make the most of it, as I
was afforded every facility by the mill officials.

I was fortunate in locating an abundant supply of the parasites
during my previous visit, for Mr. Crees, the manager, informed me that
the borer is not very prevalent in the district. My search through
hundreds of truck-loads of cane in the mill yard failed to reveal a trace
ot these insects. The particular field wherein the flies were found was an
old nursery of seedling canes which has had no trash burned, and conse-
quently afforded ideal conditions for the propagation of the borer. Then,
too, in 1910, the breeding-cages from which the tachinid {parasites
escaped were located alongside this field, and the flies have had a good
opportunity to become established.

I was surprised to learn that all of the cane of the district is burned
before cutting. This may account somewhat for the scarcity of the
borers, for the fires destroy a large percentage of those that are left in
the discarded canes; or the grubs succumb later to the action of the sun
upon the exposed stalks. Furthermore, fully 50 per cent. of the cane
grown is D1135, a variety so hard that the borers are not attracted to
it. It was instructive to note how the borers selected the softer cane
varieties in the nursery, where they had a choice.

The mill, however, now pays on individual analysis, and this is
tending to increase the growing of Clark’s Seedling and other canes of
higher density.

Rats are by far the worst pest at Mossman. Soluble strychnine
proved a failure, for the rats would not eat the bait. White arsenic has
been used there with suecess; and ‘‘Rat-nip,’’ a trade preparation
containing phosphorus, also gave good results. These poisons were
applied to pieces of bread and other kinds of food.

10 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS,

I was interested to note the scarcity of natural enemies of the
tachinid parasites in the district. The exotic ant, Pheidole megacephala,
which proved such a mortal enemy to the young flies in Fiji, is present,
but only in moderate numbers. In a few cases I found that these ants
had cleaned out the borer channels and were living in them, but, as
mentioned, they are not abundant enough to offer any serious menace to
the flies. Also, a protracted search among the cane leaves revealed only
a single jumping spider. These predators are so abundant in Fiji that
often several are to be seen on a single canestalk. Swallows were rather
abundant over the field, but I do not consider them a serious enemy to
the tachinids.

DISTRIBUTION OF THE PARASITES.

My original intention was to bring all of the flies to the Mulgrave
where the borer beetles are proving themselves a serious pest on the
low-lying lands along the river. Very recently, however, I received a
letter from the Babinda Association requesting my assistance in the
placing of some of the parasites there. <A visit to the district proved
that the pest was very abundant, and particularly so in the region out
around Moolaba.

I finally decided to liberate the flies from three centres—Moolaba,
near the station; Babinda, Dr. Reed’s farm; and at Gordonvale, on
Mrs. Moller’s farm. A cage has been established at the latter place for
breeding the flies, which are already emerging in considerable numbers.

IMPORTANCE OF THE Humus SUPPLY IN THE SOI.

I have been making further investigations at Hambledon during the
month. There, certainly, the best system of supplying humus that I have
seen is in vogue. All of the waste from the mill is composted and left
for about a year before it is put on the land.

This compost is made by building up layers of the various refuse
from the mill, filter-press, trash from the carriers, ashes from wood,
megass, and so forth. Nothing is permitted to go to waste; even dead
animals are buried in the pile.

About thirty loads of this compost, or about 20 tons, are applied to
the acre. It has proved a very valuable fertiliser, and the cane shows
a marked increase in growth where it has been applied. There is one
block near the residence of Mr. A. L. Walker (who, by the way, is a
grower of keen perception), which is a most excellent experiment. Part
of this was treated with the compost, leaving the remainder untreated.
The treated cane is almost a foot taller than the other.

The soil on this farm scours well, and for this reason it is an easy
matter to work in trash. Mr. Walker tells me that he leaves the trash
from the two last ratoon crops, 7.c., volunteering the last ratoons by
simply relieving over the rows. After the last crop is cut he ploughs
in this double trash and applies compost, or a green crop, which is
worked in preparatory to a new series of cane.

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 11

In one field, which Mr. Walker was preparing for September
planting at the time of my visit, a bean crop had been turned under,
whereafter the soil was treated with about 20 tons of compost. At this
third ploughing, the soil was distinctly blackened by the rich supply
of humus; and, though the surface was clean, Mr. Walker told me that
he intends to give it five ploughings altogether before planting to get it
in perfect tilth. Is it any wonder that Mr. Walker cuts 50-ton crops
without other fertilisers on land which was once thoroughly infested
with white grubs?

Digging pits in these fields disclosed a fair number of grubs and
several of the cocoons of the parasites (wasps), as reported last month.
The grubs are the largest that I have seen, which is probably due to the
fact that they are so well fed on the compost.

IMPLEMENTS FOR RED VOLCANIC SOILS.

Evidently the sugar-farmers have not the proper agricultural
implements for these loose red soils, for it is the general practice among
growers to destroy as much trash as possible before ploughing, because
they are unable to turn it under with the implements available.

There is urgent need for a machine that will chop up the trash or
treat it in some way so that it may be turned in with the plough. Perhaps
the rolling cutter, which is used for cornstalks in America, would work.
It is a heavy implement, drawn by a pair of horses, and the blades are
set crosswise of the row. It cuts all the stalks and trash into pieces
about 1 foot long.

The new American sulky plough, with a motor attachment for
eutting up weeds and putting them under, has received considerable
attention in our magazines. I was interested to read in the July ‘‘Sugar
Journal’’ that its fame has reached Australia, through the moving
pictures. I am anxious to see it tried on heavy cane trash.

We were able to put under a very heavy crop of Mauritius beans
on our experimental plots at Meringa, by rolling the vines well just
ahead of the plough. Treated in this way the discs of the plough, if
sharp, will cut through the vines easily, providing they are not too old.
It is best to turn the beans under when in flower, before the pods are set.
If the seed is permitted to ripen there is trouble stored up for ever after.
Not only are the vines tough and hard to cut, but the dry beans continue
to germinate in the soil for many months, some even coming along to
climb over and smother the cane after it is laid by.

LATE PLANTING.

This is one of the principal subjects of discussion at this season;
and, recently, several farmers have told me that they have known late
planting to fail because of grubs. It appears that the principal difficulty
is due to lack of cultivation. Investigation, in several instances, showed
that the soil became too wet for working just at the time when the beetles
were flying.

12 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

It must be made clear, then, that late planting will only succeed on
soils which are so easily drained that they may be thoroughly worked
during December and January. Most of our red volcanic soils are of
this character, and these are the soils which are usually infested when
planted early. Let me emphasise that it is thorough cultivation during
the flight of the beetles which is effective in grub destruction, and that
late planting is only recommended to facilitate this cultivation by
coinciding with the flight and ovipositing of the beetles.

I feel confident that the problem can be handled best on the heavy
wet soils by application of abundant humus. Since these soils scour
well, trash and green crops can be easily worked into them. After this
preparation, I would advise early planting, for there is no question that
this is best where it will succeed. The point here is that the grubs will
leave the growing roots alone if the soil is rich in organic matter.

CANE GRUB INVESTIGATION, SEPTEMBER, 1918.

With reference to the editorial, “‘Dealing with the Cane Grub,”’ in
the August ‘‘Sugar Journal,’’ we cordially appreciate suggestions from
men of experience. Indeed, the solving of our problem rests largely with
the growers themselves. Experimentation, with us, is necessarily limited
to the restricted area about Gordonvale; and it is only by free discussion
and suggestions that we can hope for early conclusions. The problem
is a tremendous one, and a man, single-handed, might spend many years
upon it. ;

Through the splendid co-operation of a few growers we are beginning
to see daylight along the lines of cultivation and the supplying of humus,
as indicated in our recent reports. Our experiments with poisons, which
are numerous, are not yet concluded. I may state, however, that I am
seeking a more satisfactory method of applying the poison than that
outlined in ‘‘ Bulletin No. 4’’ of this station. I cannot advise the open
furrow alongside the stools, because of the tendency to dry them out
too much.

D1135 vs. Goru.

In a former report I called attention to the rooting systems of these
two cane varieties. I have been following the matter up and have found
every evidence of the superiority in the ratooning qualities of D1135.
It is a cane which comes away with abundant shoots, and, therefore,
requires vigorous ratooning. It is advisable to slice right into the stool on
each side, so that too many stalks will not develop and result in a
grassy crop.

Mr. C. V. Hives, who is a man of recognised experience and ability,
has called my attention to an interesting experiment which he has had
with the two above varieties. He planted four rows of Goru down
through the centre of a field of D1135. The first ratoons on this block
were cut last June; and after ratooning the second time he found that

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 13

practically all the Goru died out, while the D1135 is doing very well.
Undoubtedly, this result is due to the different character of the roots of
the two cane varieties.

In ratooning during dry weather Goru often succumbs, while under
moist conditions it usually does well. I believe that this is due to the
fact that the main roots, which are lateral, are broken off in ploughing,
and the stool dries out. This supposition is borne out by the fact that
Goru, which was not ploughed, on the same farm is growing well.

Again, referring to the ratooning qualities of D1135, Mr. P. Wienert
showed me one of his fields at Fishery Creek, which was planted with
Badila in 1916, and the misses, which were abundant, were supplied with
D1135. At the time of my recent visit, practically all of the Badila had
been killed by the borer-beetle, while the shoots of D1135 were very
conspicuous because of their great vigour, and had not suffered in the
least from the pest.

PARASITES OF THE BORER-BEETLE.

The tachinid parasite (Ceromasia sphenophori), referred to in my
recent reports, have emerged splendidly in our cage at Gordonvale, where
they have had our close attention; but those placed at Babinda and
Moolaba have not fared so well. On two occasions we found that ants
(Pheidole megacephala) had got into the boxes of cane and were making
their nests in the channels of the borers. We have no way of knowing,
in these cases, whether the flies have escaped safely or not, and must
wait for some months to see if they become established in those districts.

We feel rather confident of the result in our own district, because
the flies were liberated from day to day, after they had mated in the
large cage; and we sometimes saw them flying about in the borer-infested
cane, which is alongside. They will have a good chance in this field, for
it is not to be cut until the end of the season, and there is plenty of other
cane near by.

BORER-BEETLES, Rats, AND OwWLs.

Let me call attention to the close relation existing between borer
beetles and cane rats; and, further on, the value of barn owls in
destroying these rodents.

It is a recognised fact that the borer-beetles work along the lines
of least resistance in depositing their eggs. If they find a split or hole
in the rind of the cane they take advantage of it; for they are able to
deposit their eggs more abundantly. The stalks chewed by rats are
ideal locations for finding the young grubs of the borer, and for this
reason I would urge that these should be discarded when cutting cane
plants.

Let us recognise, then, that the destruction of the cane rat is an
important step in the control of the borer-beetle, where soft varieties
are grown. And, again, that rats are more abundant in badly cultivated
fields, especially those with weedy headlands. I think this may be

14 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

accounted for by the fact that owls are unable to catch the rodents
thus protected. When the headlands are clean the birds are able to
discover their prey as the rats cross from one field to another.

My experience with the American barn owl (Strix practincola) will
be of interest to those suffering from a pest of rats.

A pair of these birds had been nesting for some time on the top of
a large, unused chimney of a school building. Upon examination I found
that the chimney was almost filled with the east-up pellets of the birds.
Every bird student knows how the owl regurgitates the bones, hair, and
so forth in a little pellet shortly after each meal; after raking these out
of the chimney they almost filled a 2-bushel bag; and each one repre-
sented a rodent, identified by the skull, which was entire. I took the
exhibit to a farmers’ club, where it stirred up great enthusiasm for the
protection of the owls.

I was pleased to learn from the literature here that Australia has
four species of barn owls, and that one (Strix delicatula) was said to be
common in North Queensland. Investigating the matter in the vicinity
of the laboratory, at night, I soon discovered a pair with several full-
grown young. These birds have a eall which is not unlike that of our
American species. I can best imitate it by forcibly exhaling the breath
between the tongue and teeth, making a sort of rasping sound. These
owls are very friendly and come around the buildings at night, even
perching on the water tank at the house when I imitated their eall.

This immediate region does not suffer from cane rats, and I do not
doubt that these birds are doing their part to hold them in check.

Morn PEsts.

Both the army worm (Cirphis unipuncta) and the noctuid moth-
borer (Phragmatiphila truncata) are rather troublesome this season in
places along the Mulgrave River. Fortunately, both species are attacked
freely by parasites, which keep them from becoming serious pests.

Every grower is familiar with the work of the army worm on young
cance plants, the leaves being chipped out at the edges; and the caterpillar
is usually to be found during the day hiding between the top leaves.
The work of the noctuid moth-borer, though less familiar, is easily
recognised on young canes, for the central leaves are usually killed, as all
the feeding is being done inside the shoot. On old cane the eaterpillars
work behind the upper leaf-sheaths, boring into the stalks here and there.
Their work may be easily recognised by the abundant frass they throw
out.

The caterpillars do not remain long inside the stalk, for a single
individual may make a number of tunnels, evidently only going into
them to feed, and to hide during the day. The principal damage to
mature cane is that the caterpillars cause it to shoot freely at the eyes,
due to the injury of the terminal bud.

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 15

I would suggest, as a possible control measure, the application of a
green crop of beans or peas before planting cane again. This, however,
would be of little avail if there were other infested fields of cane near by.

CANE GRUB INVESTIGATION, OCTOBER, 1918.

During the month I have done considerable travelling, and by
consultation with numerous leaders of the industry, in the various dis-

tricts visited, have been able to increase materially our knowledge of the
habits of the various pests of sugarcane.

Incidentally, Mr. Girault and I have been devoting considerable
time to the introduction of the tachinid parasites of the beetle-borer
(Ceromasia sphenophori) in infested districts. It will be recalled from
former reports that these parasites had already been liberated at Moolaba,
Babinda, and on the Mulgrave. During the past month we have secured
fresh colonies and liberated these on the Johnstone and the Herbert.
Those of the first locality were placed on the farm of Mr. R. Davis, at
Daraji; while on the Herbert they were placed at two points:—Mr.
Combo’s farm, about 25 miles upstream, and in the mill nursery at
Macknade.

INVESTIGATIONS AT MossMAN.

On all of our previous visits to Mossman we had secured our supply
of the parasites from the mill nursery ; hence I was considerably disturbed
to learn that this paddock had been burnt and milled, precluding all hope
of securing further supplies there. <A careful search of the district
demonstrated that the beetle-borers were scarcely in evidence anywhere;
but wherever found there were unmistakable signs that the parasites
were with them, and that they were completly under control. On one
farm I found these indications of the flies fully 15 miles from the mill
nursery, where they were liberated in 1910; and, what was most remark-
able, there were several miles of forest country between these two points,
with no sugarcane. Evidently the flies have travelled up the country
with the wind.

Upon the advice of Mr. C. J. Crees, the mill manager, we were able
to locate a few borers on the farm of the Crees Bros. The pest had
evidently come from a pile of discarded cane which had been dumped
alongside the field when planting, for only a small semicircular area in
the field, opposite this rubbish heap, was affected. It was also very
noticeable that most of the infested stools were rat-eaten, and the indi-
eation was that the rats had been digging out and feeding on the borer-
grubs. Fortunately, most of the grubs that we were able to find in
this spot was fully parasitised, and were the best material I have ever
seen. The benefited regions, where we are placing the parasites, certainly
owe much to the public spirit of the Mossman Mill management and to
the public spirit of the above gentleman for assisting us in cutting up
their crop to secure the parasites, without recompense.

16 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

We sometimes hear criticism of the cultivation at Mossman, and it
has been said that of the three kinds—extensive, intensive, and pre-
tensive—theirs consisted largely of the latter. This is hardly just to the
district, for the remark would never be made by one familiar with
conditions there. Most of the Mossman soils are of a type very difficult
io work under the climatic conditions. Consisting largely of clay, as
mest of them do, it is necessary to work them when the moisture content
is just right; and since they are usually either too dry, or too wet, it is
a difficult matter to turn them up without lumping. As is well recognised.
among the most experienced growers of the district, the abundant applica-
tion of green crops will do much to alleviate this condition, and put the
soil in better tilth, even without the application of lime, which is now
at a prohibitive price.

The rat pest, on some farms, is coming largely under control by
clearing out weedy headlands and other areas bordering the canefields.
This is done in some cases by fencing close to the cane, along streams
and so forth, so that stock can be turned in to assist in keeping the waste
places clean. It is an excellent idea, and if carried out generally, would
do much to put the rats out of business. It certainly offers every facility
for their natural enemies to get at them.

As indicated above, I took advantage of the occasion to try to learn
what factors were responsible for the control of white grubs in the dis-
trict. It will be remembered that this section was once badly affected.

Upon looking up the records at the mill, I found that after they
started crushing in 1897 they paid out the following amounts for beetles
and grubs collected :—

5
hes). fais 5 te a ae i 16
1S99 | ue. ae 2 ie ne steno
NEO vos id ay es ae e 88
1900) “i ae a. ase sae) ts}
190255 2 ee ve a: ae Se EODO
19035. 2. ae Es aA Ske .. 456
1904 .. Be a: 4; ae ssp 048
1905 (the last year of the kanakas) Se GO
1906... Bors ue Be 3 sae tebe

During 1906 the growers decided to test the benefit of carbon:
bisulphide, which had been recommended by French, the Victorian ento-
mologist, for the control of the grubs, wherefore they discontinued
payments for collecting the pest, and the practice was never resumed.
However, as Mr. Harry S. Staples, who was mill chemist at the time,
states in his report dated 16th August, 1910, the carbon bisulphide was
not always satisfactory, and never came into general use.

I was very much interested to learn, from the many interviews with
growers, that the factors which we have been advocating are evidently

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 17

identical with those that have placed the grubs under control at Moss-
man. These are:—Late planting and cultivation, resistant cane varieties,
nitrogenous fertilisers, and the application of green manuring or other
organic matter.

I learned from Mr. George Muntz, chairman of the Board of
Directors of the mill and one of the oldest growers of the district, that
about the year 1906 there was a general change from early to late plant-
ing, and that this latter has been the practice up to the present time.
He said that even after the mill ceased collecting grubs and beetles, as
indicated above, this pest gradually became less and less in the district.
Naturally, he concludes that late planting and cultivation is the explana-
tion.

Mr. E. D. Hunt, an American, though a recent arrival, is making
a success of a farm which was, up to the time he took it over, thoroughly
infested with grubs. The soil is sandy loam, lying along the river bank,
hence is subject to occasional overflow. Late in 1915 Mr. Hunt planted
a few acres of cane and treated it during November-December with about
a bag (160 lb.) of sulphate of ammonia to the acre. He grows prin-
eipally D1135, and has continued the application of this fertiliser to all
of his crop, with the result that he has never suffered from grubs, though
feeding-trees are abundant along the stream bordering his farm.

The farm of the late J. D. Johnson is another estate that was once
badly infested. Mr. Johnson tried every possible remedy and was a
ereat experimenter, but he had little or no success until he changed to
D1135 and late planting. His losses from grubs were immediately greatly
reduced.. There is little evidence on the place now of the presence of
erubs.

Mr. R. A. Donnelly, another director of the mill and a grower of
long experience, told me that he had no trouble from grubs for about
five years after clearing his land from the scrub, but as the soil became
poor the pest became evident, and did great damage in places, yielding
as may as twenty-six grubs under a single stool of cane. He considers
D1135 very resistant, and states that it will ratoon and make a very
satisfactory crop after being attacked, while other canes die out and
become worthless. Mr. Donnelly also considers late planting and ecultie
vation very important as grub-controlling factors, and called my atten-
tion to the success of these on. the adjoining estate, which is known as
the ‘‘Syndiecate.’’ This place, though badly infested, was cleared of
the pest by late planting and thorough cultivation.

Mr. J. M. Pringle, on a rather large estate of clay loam soil, also
believes in late planting and the application of green crops to improve
the tilth. Grubs have not been bad since D1135 was planted in 1910.
He once tried an experiment, planting B147 alongside D1185. The B147
was all destroyed by the grubs, while they did no noticeable damage to
the latter variety. Mr. Pringle uses meatworks manure on first ratoons,
and nitrates on later crops, with good results.

Mr. Pringle also informed me that Mr. Low, on the adjoining farm,
B

18 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

which was formerly greatly troubled by grubs, got good results from
late planting and thorough cultivation. The soil, he said, was too wet
for early planting, which takes place before May.

Mr. W. S. Johnson, who is managing Drumsara for 8. Johnson,
sen., began farming in the district in 1906. He informed me that late
planting was the general practice at that time. D1135 was beginning
to be used. He planted misses in a field of Goru with this variety, and
all the Goru was eaten out by the grubs, leaving the D1135 apparently
uninjured. Henee, he considers the latter very resistant to grubs.

Evidence dealing more particularly with the value of sulphate of
ammonia as a controlling factor was supplied by a number of growers
in addition to those already referred to above.

The extensive estate of the late R. O. Jones was subject to serious
losses from the grubs during the early years of the mill. He stated before
the Royal Commission (6th November, 1911) that he cultivated 450 acres
of cane in 1905 and lost 250 acres completely through grubs, representing
fully £5,000. At that time, just before he died, he said:—‘‘No human
intelligence, so far, can contend with the grubs’ depredations, and I do
not think anybody has studied the subject more than I have.’’

The estate was broken up into smaller farms and the sons took
charge in 1911. The general use of sulphate of ammonia began in
November of that year, and part of the land was planted with Mauritius
beans. The cane was planted early, yet the crop did not suffer from
grubs, and since that time they have had no further trouble. Mr. W. P.
Jones told me that all the surrounding farmers used sulphate of ammonia
persistently, and that he considers it the active agent in the control of
cane grubs.

The farm of Crees Brothers—a light sandy soil along the river bank
—was once badly affected by grubs. The former owner applied large
quantities of carbon bisulphide with little apparent result. However,
after changing from meatworks manure to sulphate of ammonia, a few
years ago, the grubs disappeared, and there has been no sign of them
since.

Mr. H. H. Smith, who has been growing cane in the district for the
past twelve years, said that his fields were formerly eaten out by grubs,
but not seriously since he began the use of sulphate of ammonia. He
plants early and applies about 3 ewt. of the ammonia to the acre, in two
dressings, during December and January. On one occasion he left a few
rows untreated in a field of Goru, and these suffered badly from grubs.
Naturally, he is a firm believer in the application of this manure.

Mr. Donnelly also experimented with sulphate of ammonia, obsery-
ing its action by digging up the stools arter if had been applied. He
found the grubs limp and inactive, though in no ease dead.

As an instance of a farm which has had no sulphate of ammonia,
I visited the place of Mr. W. Bunn, at Cassowary. The soil is heavy

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 19

elay loam and sticks to the ploughs when wet. Mr. Bunn told me he had
no trouble from grubs for several years after clearing the land, but for
a number of years now the grubs have been always in evidence. He
has used meatworks manure alone, and stated that he found many large
grubs under the stools which were blown out by the recent cyclone.

I submit this evidence, for it appears to me that it may be far-
reaching in controlling the pest in other districts. At any rate, the
practice of these better cultural methods have their principal value
outside of their relation to grub-control.

Hersert River DIstrict.

The principal canegrowing areas lying along the river have ideal soil
to work, but I was surprised to find the fields in such a weedy condition.
The great drawback, as I learned later, is the labour market during the
cutting season, the men demanding up to 30s. a day for chipping. Meat-
works is practically the only manure in general use, though sulphate of
ammonia has given excellent results wherever tried. Furthermore,
there has been no general practice of green manuring in recent years;
and I was also surprised to learn that the growers do not recognise the
value of the mill compost, for hundreds of tons of this valuable manure
is piled up in ricks and has been leaching away for years. The present
supply is being used for ordinary filling of mudholes, and the ashes for
surfacing the roads. If put up in bags this product should command
a considerable market value.

As is well known, this district was once subject to serious injury
from grubs; and, since the pest has largely disappeared in recent years,
I was interested in mvestigating the matter.

There seems to be a definite relation of grub-infestation, on the
Herbert, to feeding trees, for the areas which were infested in the early
days are now free, while the farms that suffer at present are the outlying
ones, bordering the scrub and forest, especially those in proximity to
the hills, which are covered with timber.

The management at Macknade gave me every possible assistance
and kindly furnished me itemised figures of the beetles collected in their
district during the past twenty years, with the amount of cash expended.
These figures show that decidedly the worst infestation was from 1897
to 1901; then, from 1902 to 1915 the numbers were greatly reduced, and
after the latter date, which was the year of the drought, the pest
practically disappeared, except on the farms most distant from the mills.

It may be interesting to note that during the above period the mill
paid out £11,272 17s. 10d. for 334,022 quarts of beetles, without any
noticeable decrease in the pest from year to year. The marked reduction
after 1915 was evidently due to natural causes, and was probably in no
way connected with the hand-picking.

20 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

Very little cane in this district is burned before cutting—last season
only about 5,000 out of 130,000 tons, but the trash is largely burned
afterwards, and is not conserved for humus. It appears to be the general
custom to take off only one ratoon crop and to plough this out and plant
cane again immediately.

The burning of trash has evidently had a deterrent effect upon the
beetle borers, for they are by no means a serious pest in the district.
Even on the farm of Mr. Combo, near Hawkin’s Creek, most of the grubs
were right down on the butts, and it was very hard to discover any of
the damage without first cutting cane.

Mr. W. Walker, who has been connected with the industry for the
past forty years at Macknade, gave me a number of his interesting
observations.

In the days of the kanaka, he said, the trash was removed to every
third row, and he found that the grubs were always present in these
trash rows and that the cane in these rows suffered during dry weather.
This may evidently be explained by, that the grubs, which naturally
develop under trash, are forced down into the soil by drought, and are
then compelled to feed upon the cane roots.

At another time Mr. Walker observed tlat the beetles were attracted
to the lights of the quarters, and later on, when the grubs began to do
damage, it was worst in the cane bordering these buildings, the beetles
evidently going back from the light to the cane to lay their eggs. He
also noticed that the beetle went with the wind from a fig-tree which
stood in the field, and the cane was usually considerably more infested on
that side.

Regarding the bettle-borer, Mr. Walker informed me that they were
first seen there nine years ago, and that they must have come from plants
received from New Guinea. The moth-borer, however, which is a native
insect, he said was very troublesome as far back as 1889. This insect,
which is well controlled by parasites, has done little injury in the district
in recent years.

Mr. W. Arthur, who is considered one of the best agriculturists of
the district, once suffered severely from grubs, but not for the last five
or six years. He uses green crops, which he ploughs in preparatory to
early planting. His soil is clay loam and rather heavy, but he keeps it
in good tilth by conserving his trash, of which none is burned. The
single crop of ratoons is volunteered, and the double trash worked into
the soil with a green crop before planting another series of cane. Mr.
Arthur cultivates the plant crop well, and applies about 5 ewt. of
meatworks manure to the acre. It is his intention to use sulphate of
ammonia on his ratoons during December, if it can be procured. I
noticed that his headlands and fence rows were clean, a factor important
in the control of rats and other vermin.

Evidently the immunity from losses by grubs on this farm is due

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 21

to the cultural methods, for the owner supplies the required humus and
ploughs at a season when the beetles are depositing their eggs—December
to February.

DESTRUCTION OF TACHINID PARASITES AT THE MULGRAVE.

I regret that I am compelled to report that our colony of tachinid
parasites of the beetle-borer was destroyed through the lack of co-
operation on the part of the farmer on whose place the breeding cage
was located.

The understanding was that the borer-infested field was not to be
cut until the end of the season, and that the part just around the cage
was not to be burned.

I was considerably disturbed to find, on 10th October, when I made
a visit to the cage, after my return from the Herbert River, that the
whole field had been burned and cut, and the cage had been dumped
out and torn up in moving it into the adjoining field of young plant cane.

Mr. Girault and I not only made two trips to Mossman to get this
work started, but we have also had to make frequent journeys to this

farm, so that the parasites would have every opportunity to become
established.

It is certainly discouraging to find that they now have no chance.
The flies which we liberated, having reproduced, are dead, and the
offspring are destroyed in the burning and the milling. It is only by
a miracle that any of the flies could get away.

I have not been able to see the farmer in charge of the place, for
he was away from home; but the matter was reported to the management
of the Mulgrave Central Mill, since they were so urgent that we co-operate
in the matter of establishing these parasites in the district.

THe LANTANA SEED-FLY.

I was interested to note the remarkable distribution of the Lantana
Seed-fly. It has apparently spread all up and down the coast, since its
liberation in the Cairns district in February, 1917. I found them well
established at Mossman, and even as far south as the Herbert River,
where they were found all over the district. It is certainly remarkable
that so small a fly could cross the natural barriers between the above
districts, for there must be considerable stretches with no lantana for
them to feed upon.

These insects are doing excellent work wherever established. The
eggs are laid in flowers, and the infestation is noticeable even on the
green fruit, for it becomes discoloured with brown streaks, and usually
withers and falls before becoming ripe. In practically every case the
kernel of the seed is destroyed, so that it will not germinate, This,
however, in no way affects the parent plants, which will live on for years

22 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

if not eut out. I would strongly urge every one to assist in destroying
this weed, if found on his premises, now that nature is arresting its
spread.

CANE GRUB INVESTIGATION, NOVEMBER, 1918.

The extended drought is having a serious effect upon the cane in the
Cairns district. Most of the late planting is barely holding its own,
while cane planted early in the season is showing serious drying of the
lower leaves.

In some eases, where the fields were all prepared, planting has been
so long delayed by the dry weather that the plants will not be put in this
season. This has a rather serious aspect with regard to our investigation,
for I was anxious to get the results from a number of these late-planted
areas. However, we may be able to get results from what is already
planted if the weather becomes favourable for growth and continued
cultivation.

CULTIVATION AS A ConTROL MEASURE FOR GRUBS.

As has been demonstrated, cultivation during the period that the
beetles are active seriously interferes with the laying of their eggs.
Hence, the value of late planting, which permits thorough cultivation
right through their ovipositing period.

Let me urge, then, that the cultivators be kept active in every
infested field, wherever it is possible to get through the cane. It is
important to do this work even though the ground is clean, and it should
begin not later than two weeks after the first beetles emerge. It will be
well to go over the ground at least every two weeks as long as the beetles
are in evidence.

As indicated in my previous report, it may be profitable to start the
preparation of the land which is to be planted early (April-May). The
ploughing, harrowing, and so forth, will undoubtedly have a deterrent
effect upon egg-laying in these new fields. Beetles do not like freshly
Dloughed ground, especially if it is devoid of grass and trash. Definite
observations by growers on these points will be appreciated, for they
may save us a lot of detailed experiment.

EXCHANGE OF PARASITES.

Since the breeding of our parasitic wasps belonging to the genus
Campsomeris, was so successful under artificial conditions, it has occurred
to me that these insects might be very valuable if liberated in countries
where they were free from their natural enemies. These foes are so
abundant here that the wasps are scarcely able to make themselves felt
in the open, though they breed very prolifically. Vast numbers of their
young are destroyed by secondary parasites, and the adults that do

escape probably often fall a prey to the numerous fly-catchers which
are present here.

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 23

Since Australia is the native home of numerous beetles of the family
Scarabaeidae, with great range in size, this is a fertile field for the
development of parasites; but, unfortunately for our own interests, this
parasitism has advanced to the hyperparasitic stage, 1.e., the parasites
are themselves attacked by other parasites. It is a well-recognised fact,
however, that insects introduced into new countries, where they are
freed from their natural enemies for a time, multiply by leaps and
bounds if the climate is suitable for them.

White grubs are becoming increasingly important in sugar-growing
countries, and it behoves us to work together for their control.

Our experience with these wasps has been that they are not limited
to any particular species of grub, for they are apparently able to adapt
themselves to a considerable range in size. Then, too, transportation to
foreign countries will be rather simple, since the wasps have a rather
extended pupation period.

We are hoping that we may get some relief by the introduction of
parasites. “At any rate, it is worth making the attempt. We are in
correspondence with various sugar-growing countries with this end in
view. We, certainly, stand ready to reciprocate, if our wasps are needed
elsewhere.

EMERGENCE OF BEETLES, 1918.

The long drought has delayed this emergence in many districts, so
that it is possible that many will not come out at all. Sections favoured
by the rains last month got a crop of beetles at once. About two inches
fell around Babinda on the night of 15th October, and the next day the
grey-backs were out in force. On the 19th, at dusk, I found the feeding-
trees swarming with beetles. One shrub had nothing but green beetles,
Calloodes punctulatus; others had all three species of Lepidiota:—
albohirta, caudata and froggatti, in almost this order of abundance.
There were cane lands alongside, and the shrubs were in a grass field.

Notes ON LEPIDIOTA FRENCHI.

Changes take place in the grubs of this species during October.
Both second and third stage grubs are in cells during the cool weather,
but as the hot days come on, the second-stage grubs moult, changing to
the third stage, and begin their destructive feeding. At the same time
the third stage pupate; hence it is seen that this species spends a full
year in the third larval stage. It is shortly after fhe beginning of this
stage that the insects do their worst damage to sugarcane, as indicated
in our reports published in the ‘‘Sugar Journal’’ for December, 1917,
and January, 1918.

Fortunately, this species only troubles new land, for the beetles
do not favour the laying of their eggs in old fields and prefer blady grass.

24 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

CANE CRUB INVESTIGATION, DECEMBER, 1918.

Since weather conditions at our station continued too dry for any new
developments, I improved the opportunity to visit Mossman, where heavy
rains had fallen early in November. My main object, this trip, was to
study the comparative emergence of cane beetles; and, incidentally, to
note the various feeding-trees.

Conditions at Mossman are excellent just now. There is abundant
feed for stock, the cane is of fine colour, and cultivation is going on every-
where. The soil is just moist enough for ploughing, and the farmers
who have land for early planting are beginning the preparations. Their
practice cannot be too highly recommended, for horse work at this season
is what counts against the beetles.

EMERGENCE OF CANE BEETLES AT MOSSMAN.

The rains coming in abundance, as they did in this district, brought
out, practically, the full crop of beetles, so that they are not stringing
along over several months as they did in the Cairns district last season.
As indicated in my previous report on this district, I did not expect a
very large emergence, for there had been no serious damage in recent
years. Hence I got a surprise when I walked out to the river, on the
evening of my arrival, and found the two large figtrees near the bridge
literally swarming with grey-backs and the foliage mostly riddled.
Careful search during the remainder of my week’s stay failed to locate
any other similar congregation of the pest. A few cane beetles could be
found almost anywhere, on the feeding-trees, but not in serious numbers.

Even at Mango Park, where the beetles did so much damage in
former years, they were scarcely in evidence. I could only locate a very
few on some of their principal feeding-trees, and Mr. Hearn, the new
manager, informed me that there were no beetles flying at night. The
cane on this estate looks fine in spite of the setback caused by the long,
dry spell, and there is every prospect for a successful crop.

Along the river, at the farm of Crees Brothers, I found a few grey-
back beetles on mandarin trees, and Victor Crees, who is managing the
farm, told me that the beetles swarmed at night on a large rubber tree
by the house, but I was not able to locate any upon it.

Examining the low bushes along the roadside, just at dusk, I found
a few of both Lepidiota frenchi and L. caudata, with considerable
numbers of very small cane beetles belonging to three species. All of
these go back into the soil after feeding, so that they are never seen
during the day feeding, or on their feeding-plants.

In the field alongside this road, belonging to Mr. Mullarvey, we
found full-grown frenchi grubs; and though they appeared to favour the
bunches of Guinea grass along the headlands, they were undoubtedly
doing some damage to the cane, for it was yellowing in places. These
grubs will continue to work until next May, when they go into resting
cells, to emerge this time next year.

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 25

Mr. R. D. Rex, a prominent grower at South Mossman, told me that
his place never suffered from grubs, though the beetles were always in
evidence about the feeding-trees in his yard. He said that the beetles
simply swarmed about the figtrees at night, and that the coconut leaves
were badly eaten by them. We saw many beetles on these palms.

Mr. Rex always plants early, which is evidently best for clay soils;
but his practice of thoroughly preparing the ground by doing the horse
work while the beetles are on the wing probably saves him from grub
attack.

Mr. Rex made the interesting observation that fruit bats congregate
in beetle-feeding trees, even where there is no fruit for them to feed
upon. He found the ground strewn with broken parts of beetles next
morning, indicating that the bats had been feeding upon the insects. We
would appreciate any further evidence along this line.

The Mowbray district appears to be free from grey-backs, for I
could not find a bettle on the feeding-trees. Following up the report that
grubs were in evidence at this season, I found that the frenchi grubs
were doing slight damage in some of the newly-planted land. The pest
was only noticeable on the high spots in the field, where the humus is
naturally washed out of the soil. The cane in the low places was growing
strong, with no sign of injury. I also noticed that bandicoots had dug
holes in search of grubs in the infested stools, but had not molested the
healthy cane.

FurTHER EVIDENCE OF THE EFFECT OF LIGHT ON THE GREY-BACKS.

A benzine lantern of high ecandle-power was taken under the feeding-
trees by the Mossman Bridge, and the beetles began swarming around it
at once. An ordinary lamp, though giving much less light, appeared
equally attractive, probably because, having no cover, the rays went
straight up into the tree. I was told that placing the lamp upon a white
sheet made it more effective, for the white surface acted as a reflector ;
and by this means the beetles could be more easily gathered up.

It is my experience that these beetles are much more easily attracted
to lights soon after emergence than they are later on, when almost ready
for ovipositing.

FEEDING-TREES OF THE BEETLES.

By a thorough examination of the scrub, which at Mossman borders
most of the cane land, I was able to note the principal feeding-plants of
the grey-back beetles. This examination is facilitated by the fact that
this species remains on the feeding-plant during the day.

Several new feeding-plants were observed, some of which we are not
yet able to name, being unfamiliar with the scrub flora. However, it
will be interesting to know that the Candle Nut (Aleurites molucanna),
a tree with broad, coarse leaves, is much sought after by the beetles, and
the foliage is often eaten right to the midribs. Since these plants are
so generally distributed it will be well for canegrowers to recognise

26 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

them. They bear clusters of nuts on the ends of the outermost branches ;
and these spherical fruits form an important food of the cassowary.
The tall, straight, light-coloured trunk and broad leaves make the plant
easy to identify. Other synonyms are Tar-kal and Nappalla.

As is well known, the leaves of all the species of figs are eaten, and
I found that the cluster-fig was a favourite, the trees being almost
defoliated within a week after the first emergence of the beetles.

As mentioned above, the leaves of the coconut palms were riddled,
and | found that bananas suffered as badly where the beetles were
plentiful. Mandarin and orange trees are also attractive, though I
found no beetles on the rough lemons.

At one place along the border of the cane I found a clump of white,
or silver, wattle, with many feeding beetles. These trees are evidently
very attractive from the fact that I found no beetles on a large figtree
close by.

I will be able to add several to this list when I secure names for the
other feeding-plants that I observed.

WIREWORMS.

There is evidence that this pest is doing some damage at Mossman.
Incidentally, it may be mentioned that this pest is also a native of the
virgin grass land, and favours low-lying fields. The adult is the common
snap-beetle, which flips up when placed upon its back.

I found the cane, in places, covered with a small, dark-coloured
species, many of them in the act of mating. They were so thick that
often a dozen could be taken together on a leaf.

The damage from this pest is principally the destruction of the eyes
on young sets, resulting in numerous misses. Their work is easy to
recognise if the injured set is examined carefully. Usually the wire-
worms eat into the pith at the ends of the set while waiting for the eyes
to expand. The insects also feed upon the young roots.

Control measures are most difficult, since the wireworms seem to be
immune to even the most violent poisons. In practice, cultural methods
offer the only relief, and even then we must know the life-history of the
particular species with which we are dealing, so as to plant at a time to
avoid the larvee.

It has been found that these insects cannot be starved out, even by
keeping the ground fallow for a year, and they pay little attention to
deterrents. They are certainly a pest that will require careful investi-
gation before we can hope to do much against them.

I had a brief experience with this pest In Fiji, and I soon saw that
ordinary control measures were of no avail. Looking up the literature
on the subject I found that other experimenters had come to the same
conclusion.

“SaaW LT

A200 yeas

“iX0¥)

\~as wad sana ABQ abvisaw MOVE So amby 4
* $2 ay burpory =+4
"SwAwyd BT M™MT-PYPPG A

. maw B\OAUPAC +)

ONIGHEYY CL NOLLVIOY HLIM SAN) dO NOILOAIULSI(
0 « '

MWAH AYO g
eaai{e

DNIMOHG WUVy

XBN0 PYYAS

MOOOY ct
wna ob

th

/

24 «||

| Face Page

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 27

CANE GRUB INVESTIGATION, JANUARY, 1919.

Fortunately, we are at last experiencing ideal growing weather,
and even the weeds are coming on apace. The cane never looked better.

BEETLE EMERGENCE.

Really our first good rains did not come, at Meringa, until 19th
December, though we had a brief downpour on the 28th of November
that brought out a few beetles.

Both the grey-backs, Lepidiota albohirta and L. frenchi, have come
out in great abundance this year, this being the time for the regular
biennial occurrence of the latter species.

The extreme abundance of frenchi has made it possible for us to add
materially to our knowledge of the habits of this species. Since they do
not remain on the feeding-trees during the day, like the grey-backs,
there has been less opportunity to study them.

Upon the approach of darkness these smaller brown beetles crawl
up out of the grass where they have been hiding, and for about ten
minutes everywhere about you is one seething hum of the insects. The
females settle first, upon any low object—bushes, dry twigs, or even
upon the fences—and mating at once takes place. Usually several males
cluster about one female, but as soon as one secures connection he lets
himself fall backward, so that he hangs head downward, and the other
males fly away. The pair remains in this position, perfectly motionless,
for about twenty minutes, when they separate and fly to their feeding-
trees, where they remain until morning. Soon after daylight, about half
an hour before sunrise, they again become active, leaving the trees in one
concerted flight, which lasts for about five minutes, when everything
becomes quiet. In place of going straight into the ground the beetles
usually settle upon the stems of any convenient plant, about 18 inches
from the surface; here they remain perfectly motionless for several
minutes, then proceed slowly downward into the grass, and finally enter -
the soil. It is this habit that makes them an easy prey to the ‘‘early’’
bird.

Birps A VALUABLE ASSET.

Soon after the first flight of the beetles this year, my attention was
attracted by a flock of fowls and ibises under one of the large rubber
trees in the Mulgrave Mill yard. They were all actively feeding upon
beetles which were dropping out of the tree. Upon closer observation
I saw that there were a number of smaller birds in the branches, and
these, too, were eating the insects. Usually when one of the birds hopped
on a twig and secured a beetle, several others were dislodged and fell
to the ground, where they were quickly gobbled.

I have followed up this interesting line of observation, using my
6X binoculars, with excellent results. Ordinarily the birds are very timid

°

28 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

in this district, because of a lack of effective protection, and scatter
before one can get near enough to see what they are eating. By approach-
ing quietly, however, with the glasses I have been able to observe most
of our moderate-sized birds feeding upon the beetles. It may be interest-
ing to note a few of these, such as the magpie lark, yellow-belly, leather-
head, butcher bird, mynah, satin bower bird, blackbird, laughing jackass,
&e. The first two are by far the most numerous, and have the advantage
that they follow their prey to the ground if they fail in their first
attempt at securing it.

Most of these birds are too small to swallow the grey-backs at one
mouthful, but when near enough one ean see that the birds beat the
insect to pieces on the larger branches before attempting to swallow it.
Then, too, the quantity eaten by a single bird is limited, but they make
up for this in numbers. Just after daylight there is a constant stream
of the birds through the feeding-trees of the beetles.

As will be noted above, even the fruit-eating birds take kindly to the
beetles during this, their nesting season, a fact which agrees with my
experience in America, where most of the seed-eating birds feed their
young upon insect diet.

Protection of the bird-life of a country is certainly worth considering,
for we cannot over-estimate their value to man, even of those birds which
we sometimes class as enemies, when they occasionally eat our corn or
kill our chickens. Undoubtedly, birds are:the greatest factor in the
control of insect pests.

Theoretically, almost any minute insect, with its rapid methods of
multiplication, would overrun the earth, making is impossible for man
or other animals to exist, if the offspring of insects all survived and
reproduced.

This has been forcibly illustrated by T. Bainbrigge Fletcher; in his
work on “‘Some South Indian Insects,’’ where he takes the case of an
insect laying only two hundred eggs and having a life cycle of one month.
Starting with lst January for convenience, a single fertilised female
lays 200 eggs, all of which hatch and mature by the end of the month;
on the average half of these will be females, each of which will lay 200
eggs on Ist February, and by the end of February we have 100 « 200 =
20,000 mature insects, of which half again will be females laying between
them 10,000 x 200 2,000,000 eggs. Continuing, simple calculation
shows that by the end of the year the descendants would reach the
prodigious total of two septillions (2,000,000,000,000,000,000,000,000)
of individuals. The human mind is quite incapable of grasping the
significance of such a figure, but a few comparisons may assist the
imagination. If 1,000 of the insects weighed only 1 oz., their united
weight would be 558,035,718,571,425-5 tons, and if 1,000 measured 1 eubie
inch, they would cover an area of almost 50,000,000,000,000 square miles,
with a uniform. layer 1 inch deep. Taking the dry surface of the whole
earth to be 51,000,000 of square miles, they would cover the whole of
this to a depth of over 81 feet.

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 29

- Figures such as these are suggestive of what might take place if an
insect meets with particularly favourable conditions for development.
Probably the most important of these are: (1) favourable climates; (2)
abundant food; and (3) freedom from enemies.

Nature is usually. nicely balanced, so that no species becomes
predominent. Man, however, is often the means of upsetting this balance
_ by transferring insects to new countries, where, removed from their

natural enemies, they often become serious pests; or, again, by cutting
the forest, he interferes with the nesting of insectivorous birds, &e., with

the result that his crops are destroyed until Nature is again able to
maintain her balance.

It is now well recognised that man is able to greatly assist Nature
in regaining this equilibrium; and much has been done by the intro-
duction of insect parasites. It is possible, however, to do just as important
work by encouraging the birds through protection, &., so that they will
multiply near our homes.

CULTIVATION EXPERIMENTS.

I have started an extensive series of cultivation experiments, with
proper checks, at the Greenhills Estate, on fields which are regularly
destroyed by the grubs. These experiments cover both plant and ratoon
crops, and we ean hope for some very interesting results within a few
months, for the cane is an excellent stand at present.

Three types of implements are being used, harrow, Planet Junior,
and plough, and I am also trying different intervals to determine how
often it is necessary to stir the ground and disturb the beetles.

The cane in the Meringa plots is a perfect stand; and, though it
was planted in April, it got such a setback by the drought that I am
still able to keep the horse going through it. I am hoping for results of
this intensive cultivation within the next two or three months.

Noctuiw Moru-Borer, PHRAGMATIPHILA TRUNCATA, Walk.

Mr. P. H. Edington, at Deeral, has suffered considerably from this
pest. The insects have continued for several months on his plant cane;
and he told me that he had renewed fully 75 per cent. of the plants in the
worst-affected field. At the present time the cane is almost free from
attack, and as high as one’s head, but very uneven, due to the fact that
it has been supplied ‘at various times.

~ [T was not able to locate any of the parasites, though at the time of
my visit it was a very difficult matter to even find a caterpillar of the
moth in the infested stalks ; most of the runs of the borer had been cleared
out by the brown ant, Pheidole megacephala.

30 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

CANE GRUB INVESTIGATION, FEBRUARY, 1919.

The unprecedented dry weather, for this time of the year, is having
a rather serious effect upon the late-planted cane. It is just the
condition for the rapid development of the cane grubs, and they are
already beginning to show by the yellowing of the cane in a few places at
the Greenhills Estate. Out of 181 grey-back grubs picked up behind the
plough, 22nd January, in Field E1 of ratoons, 68 were in the first stage,
112 in the second, and one had already reached the third or final stage.
Digging under the yellowing stools of ratoons in E2, 5th February, I
found an average of six grubs, mostly in the second stage. This field is
in the worst-infested area, and suffered severely last season, so it is not
surprising to find that the infested, stools have no roots and ean be
easily pulled out with one hand.

It will be of interest to record that grey-back beetles were still in
evidence on the feeding-trees, 5th February, and dissection showed that
these stragglers were full of eggs. This was just about two months after
the first beetles emerged in this district, so the period for cultural control
has been somewhat extended.

I have improved the opportunity during the past month for securing
further data on controlling factors—both better cultural methods, and
the all-important one of feeding-trees.

BENEFITS OF INTENSIVE CULTURAL METHODS.

Recently I was most gratified by an interview with Mr. David
Hunter, a man of long experience in the sugar industry on the Johnstone,
whose record as a grower has been so successful, especially in the handling
of grub-infested land, that his observations should have the greatest
value.

Mr. Hunter first came to the district about twenty-eight years
ago, taking charge of land for the Colonial Sugar Refining Company,
which grew its own cane at that time. He was quick to notice the value
of filter-press on cane land, and became an advocate of intensive surface
cultivation.

About 1906 he took up one of the company’s farms, which had been
thrown out of cultivation for years because of the grubs. This pest
had been so severe in the early days that the land was not considered
profitable to grow cane; hence he got the place on very reasonable terms,
and, being near the mill, he made arrangements for the complete output
of compost. Mr. Hunter began applying this in 1908, and by thorough
cultivation soon had the farm in perfect tilth, with not a weed in sight
anywhere, and he kept the cultivators going so that none would show.

I was interested to learn that Mr. Hunter believes filter-press is
rather attractive to grubs, and that he found ammonium sulphate to be
the opposite. Anyway, he says that he has seen cane treated with this
latter chemical standing and perfect, while untreated cane alongside had
fallen because of the grubs. He does not agree with the usual statement,

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 31

that ammonium sulphate robs the soil. In this he is in accord with the
most up-to-date knowledge of fertilisers. He says that there is no ques-
tion, but that this chemical brings about a bumper crop ; hence, a portion
of all the available plant-foods are used up, and these must be renewed
from time to time. For this purpose he used meatworks manure. He
also returned to the soil all of the waste from the crop. No trash was
burned. He accomplished this by relieving into every other row when
the plant-crop was cut, and applied manure and cultivation in the free
middles. The trash from the first ratoons was relieved into the middles
which had been cultivated, and the alternate ones were broken up and
fertilised. Finally, the trash from the second ratoons was left, and the
whole thing ploughed in. He used this regular system of three crops
before ploughing out, and says that late planting is the right thing for
that class of soil. It is needless to say that he had no trouble from grubs.

Then, too, results were apparent in the crops he took off, which were
double or treble those of adjoining farms, and in one case I found by
the mill records that he cut 43 tons per acre, when his neighbour across
the road, on the same class of soil, cut 9 tons—the difference being due
entirely to better cultural methods.

THE QUESTION OF /EEDING-TREES.

Mr. Hunter is also a firm believer in the destruction of feeding-
trees, because he says the grubs move back as the scrub is felled. He
advocates removing the serub and pasturing the land for half a mile
back from all cane areas, using cane pest destruction funds to assist in
this work. He said that the owners of the scrub would, of course, pay
part of the cost, and the mills could make use of some of the wood to
help out on the expense. Cost of felling and burning would be, approxi-
mately, £5 per acre at this time.

Mr. C. E. Jodrell, who is another pioneer of the Goondi district,
also obliged me with some of his very valuable observations. He is one
of the most extensive growers to-day, having come on to his farm, in
the stumps, twenty-five years ago. In those early days the grubs often
ate everything out, so it was the exception to get even a 15-ton erop.
He told me that the beetles were then in hordes in the feeding-trees just
behind his house; and that the flying foxes made havoe among them,
so that the remains of the beetles were several inches deep on the ground
in the morning. The broken parts of the grey-backs could be plainly
seen in the excrement of the bats.

I was interested to learn that there has been no trouble from grubs
on this farm since the scrub was cut on the hills surrounding it, about
eighteen years ago.

Mr. Jodrell also owns a farm at Daraji, and he told me that he
always had trouble from grubs on the part bordering the serub, but
that there is no injury in the fields lying about half a mile away from
these feeding-trees.

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

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 33

fields le well within the one-half mile limit from feeding-trees. Here
the worst infestation was on the high ground, where the beetles would
naturally come to rest from their flight. It must also be noted that these
high spots are naturally poor in humus, and consequently the work of
the grubs is more quickly noticeable. ‘

FreLtp EXPERIMENTS.

The cane in the cultivation plots at Greenhills is at present looking
well, especially the plant cane in fields D1 and D2. Unfortunately, I was
unable to get the cultivation started as early in the flight of the beetles
as I desired, and in the ratoon field E1 it was almost a month late, in
some of the plots, so that small grubs were turned up at the very first
treatment. It will be noted from the map that all three of these fields
border the feeding-trees and have always been the ones most infested,
so we are hoping for some rather conclusive results in spite of our late
start.

It will be interesting to note from the map that the fields L6 and
L7 are in the badly infested area, but, as I have previously noted, a
successful crop was secured from these at the last cutting. The lower
half of L6 was planted near the end of September, 1917, and after late
cultivation produced an excellent crop; the upper half, planted in June,
1917, was a failure, because of the grubs, which put the cane down in
February, 1918. The field L7 was planted about the first of October,
1917, but had rather poor cultivation and was pretty weedy. In spite
of this the crop was fair, indicating that even the horse-work it got
disturbed the grubs so that they were held in check.

CANE GRUB INVESTIGATION, MARCH, 1919.

The heavy rains which started on the 25th of February have saved
the day in many of our cane fields. Conditions were prime for the
grubs, and they were getting in their work to an alarming extent. <As
usual, Greenhills was the first to show the characteristie yellowing in the
affected portions. Some of the ratoon fields lying near the woods have
already succumbed, in spite of the rains.

F'EEDING-TREES.

Continuing the study of the relation of feeding-trees to infestation,
I have made further interesting observations, and can now say with some
confidence that the beetles travel approximately half a mile when going
with the wind, but scarcely any against it. These conclusions are based
upon numerous observations in a number of localities, and in no case
have I found evidence to refute these conclusions.

As pointed out last month, the infested areas at Greenhills lie princi-
pally within the half-mile limit, and the worst infestation is in the
higher parts of the fields lying near the feeding-trees.

Cc

34 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

I have recently instituted careful surveys in the infested areas by
counting the number of grubs per stool of cane. As a typical example
of this method, I may eite the field of first ratoons, H1, at Greenhills,
where, by working at a gradually increasing distance back from the
forest, we got the following grubs:—14, 13, 15, 8, 3, 1, the last stool
being just about on the half-mile from feeding-trees, to windward.
Another excellent example, which works out in perfect accord with this
theory, is an infested farm near Gordonvale. Feeding-trees border it to
windward, south and east, and the principal infested areas are on the
side towards this timber. The worst-infested fields, A and EH, are.now
out of cultivation, having failed completely last season. However, I was
able to get the following remarkable figures, by taking the average of a
series of stools :—

12 chains from the forest, 45 grubs per stool, Badila, 1st ratoon.
16 chains from the forest, 17 grubs per stool, Badila, 1st ratoon.
18 chains from the forest, 13 grubs per stool, Badila, Ist ratoon.
22 chains from the forest, 12 grubs per stool, Badila, 1st ratoon.
28 chains from the forest, 7 grubs per stool, Goru, Ist ratoon.
35 chains from the forest, 5 grubs per stool, Goru, 1st ratoon.
40 chains from the forest, 0 grubs per stool, Goru, 1st ratoon.

The same decrease in the number of grubs per stool is shown in
every part of the farm as one recedes from the feeding-trees.

CULTIVATION EXPERIMENTS.

As stated in my last report, I was unable to get these experiments ©
started in time to derive the maximum benefits therefrom. Nevertheless,
the experiments show that there is no material difference between work-
ing the soil once a week and once a fortnight; also, that the plough is
considerably more effective i disturbing the grubs.

Every Week.
Plough .. ae .. Average number of grubs per stool, 5
Cultivator a .. Average number of grubs per stool, 83
Harrow .. ols .. Average number of grubs per stool, 93

Every Fortnight.

Plough .. ae .. Average number of grubs per stool, 6
Cultivator Sic .. Average number of grubs per stool, 8
Harrow .. 46 .. Average number of grubs per stool, 72
Check?) ae nt .. Average number of grubs per stool, 133

The check in this case does not show its true value, because it was
cultivated twice after the experiment began in spite of my instructions
to the contrary. Still, the better cultivation in the other plots is very
noticeable from the figures.

There is very decided evidence that cultivation as a means of control
must begin during the two weeks after the beetles emerge, before they
start laying. Apparently, once the eggs are deposited it is a difficult

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

36 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

results. Along the south side of the field, where we had previously found
an average of forty-five grubs per stool, 1 could only get an average of
five. No dead ones were visible in the soil, having probably rotted and
been carried away by ants. This was the part treated on one side only.

In the middle of the field, where the stools received treatment on both
sides, I was unable to find a single grub, and there was a vigorous growth
of new roots starting. The cane tops also looked beautifully green, with
no sign of injury from the treatment. I had previously found an average
of thirteen grubs per stool in this location. Evidently the rains which
followed, a day or so after the application, saved the cane from any
ill-effects of the chemical.

I also found that the grubs were still numerous on the untreated
portion, and the cane was showing a very noticeable withering, in marked
contrast to the treated plants.

EXPERIMENTS WITH NITROGEN FERTILISERS.

Our field experiments with these chemicals are not completed, but
there are some observations which should be noted. Experienced growers
know that the best results come from the application of these fertilisers
after the rains begin, when they give to cane-growth the maximum
impetus. In our experiments with nitrate of soda and sulphate of
ammonia to determine their specific value in making the cane resistant
to grubs, I find that where these chemicals were applied during the dry
weather in August their effect upon the growth of the cane has not been
perceptible, and in the treated field at Greenhills the grubs are showing
considerably. On the other hand, where ammonia was applied during
January the cane shows a remarkable development and improved colour ;
and though I found grubs under some of the stools, the numerous new
roots are keeping up the vigour of the plant. In another month the
contest will be decided, for this is the worst season in the activity of the
grubs.

Im order to determine the direct effect of these chemicals upon the
grubs, I placed grubs in soils with varying amounts of the fertilisers,
giving them no roots to feed upon. The experiment was carried along
for ten days with no noticeable effect. Several of the grubs became
injured and died, but those that remained were perfectly normal at the
finish. I would, therefore, conclude that the control exerted by these
chemicals les principally in the increased vigour they impart to the
plant.

EXPERIMENTS WITH MoLASsEs AS A Bart.

One might naturally conclude that molasses would be attractive to
grubs if placed in the soil. It was recently suggested that this would
act as a valuable bait if mixed with poisons. Experiments, however, have
demonstrated that the grubs will not eat it—at least, not enough to be of
value. Where the same amounts of arsenic were used alone in the soil,

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 37

results were very rapid; the grubs dying in from one to four days. Even
the dry white arsenic gave splendid results. As this chemical has a great
affinity for humus and remains in the surface soil for years, it may prove
best to apply it in the drill at the time of planting, or perhaps dust it
around the young plants, so that the grubs will come in contact with it
when they begin their depredations.

INTRODUCTION OF PARASITES.

That we may leave no stone unturned, I have continued investigation
of the valuable parasites of white grubs in other sugar-growing countries.
There are a number available, though it is problematical whether they
would prove of value against our native insects. Anyway, it is worth
trying, for if we can induce them to attack any of our numerous
Searabeids (root-feeding grubs) the expenses of introducing the parasites
will be well repaid. These valuable insects are doing excellent service in
Hawai, Porto Rico, Mauritius, and other countries.

It will be interesting to quote from a letter just received from D.
D’Emmerez de Charmoy, entomologist of the latter country. He says:

‘“‘There are several parasites of white grubs here. Apart from
Dielis rufa, an indigenous species parasitic upon two of our melolonthid
grubs, Rhizotrogus gravidus and Rhizotrogus pallens, the others have been
introduced.

‘‘T am sending you a copy of a bulletin on the introduction of T'yphia
parallela, in which you shall find a detailed account of the introduction
of this parasite, as well as a general description of the spread of its host,
Phytalus smathi.

‘‘The other principal pest of sugarcane is Oryctes tarandus, which
has lately been the cause of considerable damage to canes in certain parts
of the island; so much so that I went to Madagascar, in 1917, for the
purpose of bringing over certain Scoliids, which I thought might prove
parasitic upon Oryctes tarandus. The details of this introduction are set
out in the report I am sending you.

‘*Sinee the publication of this report, Scolia oryctophaga has been
found in places where the insects had originally been liberated, so that
I think the parasite to be definitely established. Its effect in checking
the spread of Oryctes tarandus is now only a question of time.

‘‘T am extremely interested in the work tndertaken in Queensland
for the purpose of controlling cane grubs, and feel certain that your
eftorts will result in complete success.

‘‘Tt would be a real pleasure for me to help you in any way, should
you require my services.”’

38 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

CANE CRUB INVESTIGATION, APRIL, 1919.

The abundant rains, in the beginning of April; have improved cane
conditions materially Even the fields suffering from grubs have
improved where they were not already too far gone.

During the past month I made a survey of the Herbert River dis-
trict, and found a most gratifying scarcity of grub-injury.

HerBert River District.

This district, hke the Mulgrave and most other cane areas, has
suffered for rains, with the result that they will harvest only about half
a crop. The lack of grub-injury this year is very fortunate. Even in
the areas that were formerly badly infested the grubs are not showing,
and digging under the stools failed to reveal them.

The only assignable reason for this immunity is that cultivation
has been continuous, because of the dry weather. The farmers in some
areas told me that a good lot of beetles were on the wing; and the lack of
foliage on the feeding-trees in these localities bears out their statements.
In several localities, however, where the beetles were very numerous in
former years, they did not appear at all this last season; in fact, beetles
have been searee since the drought of 1915.

During my limited time I was able to make a thorough survey of
all the cane areas which had been infested in recent years, through the
generous assistance rendered by the officers of the C.S.R. Company’s
mills. In very few places were we able to locate any grubs by digging
under stools, and in no case were there enough to do serious harm. This
is certainly remarkable, and must be due to the better cultivation this
rear.

: I had a communication recently from Mr. J. Wittrup, president
Halifax Planters’ Club, urging me to visit the district. He took me to
several farms which had suffered in former years from grubs; but there
is no indication that the crop is going to suffer this season. These

farmers use meatworks manure, and the cane is of a fine dark-green
colour.

Mr. Wittrup called my attention to a small field (A. Baxter’s) lying:
alongside a forest of young Moreton Bay ash trees, which were almost
defoliated. He told me that the beetles were exceedingly abundant in
this timber, and that the cane never suffered from grubs. It is certainly
a notable example of the relation of prevailing winds to infestation, for
these feeding-trees lie to leeward of the cane, and the country to windward
is all open and without a tree within half a mile.

Mr. W. Walker, at Ripple Creek, told me that he is ploughing up
considerable numbers of grubs where he is turning down beans, and that
the beetles were abundant on feeding-trees near his house this year,
but that the cane has never suffered on either side of the creek. The

soil is rich alluvial deposit, which may, possibly, account for the
immunity.

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 39

Mr. Walker also remarked that the birds did good work on the
beetles, which emerged over a very long period this year.

The farm of D. and E. Mullans, near Hawkins Creek, though not
showing the usual infestation from grubs, has a most interesting experi-
ment with sulphate of ammonia. They applied the chemical to twenty-
two rows in a field of Badila ratoons, using about 2 ewt. per acre. The
treated cane is a beautiful dark-green colour, and about double the size
of the remainder of the field, which is very yellow. The fertiliser was
appled at just the right time, after the rains started in January.

The farm of Combo and Co., which lies in the same narrow
valley, shows no sign of grubs in the places where they have appeared
every year. Mr. Combo told me that he eut the feeding-trees along the
stream before the beetles flew in December. There are other feeding-
trees, however, within half a mile to windward, so I presume that the
late cultivation has done as much here in making the cane free from
grubs.

A visit to the newer cane areas far up the river on the Victoria
side, revealed no infested fields, even where grubs did considerable
damage last year. The dry weather has stunted the cane in places, but
there is none of the characteristic yellowing caused by grubs.

. Mr. E. Freeman, cane inspector at Victoria Mill, called my attention
to a farm belonging to Mr. M. Deloughery, in the ‘‘Pocket,’’ which has
produced seven crops of cane right among the trees, without any culti-
vation. This farmer has had no trouble from grubs, and cuts 50-ton
plant-crop. The feeding-trees are on every side. It is a case hard to
understand, for Mr. Cole, on a farm alongside, cultivates his cane and
has had trouble from grubs since the second crop on new land. The
serub, with fig and other trees, is to windward, but Mr. Cole is having
these cut out, so we shall have an opportunity to note the result upon
future crops.

Mr. W. Tooth told me that he has had trouble every year with grubs
on his high ground, but none are showing this season, although feeding-
trees are abundant to windward.

Mr. Tooth says that the cane laying near the serub is not so badly
infested as that on the ridge further back. This observation agrees
with our experience, for the beetles naturally come to rest on these
elevated spots.

The distribution of grubs is not always easy to explain, but in
every case where they have infested fields in former years there are
feeding-trees to windward, within half a mile, to account for their
presence.

It is interesting to note that none of these infested fields are in the
older districts, where the feeding-trees have been cleared away, though
the land was infested in the early days.

40 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

GREENHILLS ESTate.

Entering the plantation on the north, everything appears most
favourable for a good crop; but as soon as one passes the high ground
at the centre of the estate a terrible scene of devastation opens up. It
looks as if a severe drought had struck it, in many places the tops being
entirely dry. Fortunately, this year there has been no severe winds, and
very little of the cane has fallen. The roots of these drying stools are all
eaten off, however, and it is an easy matter to pull them over with one
hand, for the soil is exceedingly friable.

A bird’s-eye view of the estate under these conditions is most
instructive, for it shows, decidedly, what I have been trying to emphasise
in recent reports, that infestation has a very definite relation to the pre-
vailing winds and feeding-trees. The part of the field adjoining the
feeding-trees, to windward, is often less injured than that of the higher
ground further back, as I have noted above. Evidently the beetles, in
their blundering flight, follow the lnes of least resistance, and come to
rest on any elevated area. At any rate, it is common experience that
the high ground is most severely affected; it is always in these parts
that the injury first appears, possibly because the soil is more leached
out and poorer.

It was most distressing to observe soon after I sent in last report,
and before the refreshing rains, that the splendid cane of F3 was about
to succumb. It will be recalled that part of this field was treated with
a green crop of Mauritius beans, the effect of which was most remarkable
upon the cane. The grubs were very noticeable in the untreated part
of this field a month ago, but the cane of the treated portion continued
a healthy green and had every appearance that it was going to resist
the attack. The dry weather continued too long, however, and this
beautiful field went brown in a week. Evidently the extra humus of the
beans was not enough to carry the grubs over the trying period. With
abundant, normal rainfall, however, the cane would doubtless have come
through in good shape. Anyway, the added humus staved off the injury
for more than three weeks, thus showing that this is a step in the right
direction.

A second disappointment has been the field C3 treated with sulphate
of ammonia. Like the beans, this chemical showed a marked stimulus
to the crop, and at the time of writing last report I had great hopes for
a successful result. The lack of rain, however, proved too trying, and
the cane finally went yellow.

Arsenic at the rate of 10 lb. per acre sprayed or dusted on the
vegetation at the time of ploughing the ground preparatory to planting,
is proved to be of little or no value in destroying the grubs. All of the
plots treated in this way have succumbed. It may be necessary to use
more of the poison, but before we draw any conclusions we must await
the results of other experiments. Those we have under way indicate
that the poison has considerably more effect when applied near the roots
of the young plants.

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 41

ON THE VALUE OF CULTIVATION.

Standing out in marked contrast to the surrounding devastated areas
are the fields which chanced to get intensive cultivation at just the
critical time. In each of these cases the planting was late (October),
and, consequently, the cultivation followed through the flight of the
beetles. The field of first ratoons (lower half of L,) is showing most
remarkable growth, and only slight infestation on one edge. It was cut
in November, and the ratooning coincided with the flight of the beetles.
It certainly now looks as if we would get another good crop in the midst
of this infested area, with no other treatment than proper cultivation.

Then, too, the 40-acre field of plant-cane, J,, still has a fine dark-
green colour, in marked contrast to the devastated fields on every side
of it. Only in a few spots along the tramline is there any indication of
grubs, and these do not appear to be spreading, for the recent rains have
improved the colour and vitality of the cane.

Digging shows that the grubs are beginning to go down. Many are
yellow, showing that they have finished feeding, so the most of their
devastation is probably over. Continued rains may possibly revive much
of the injured cane if it has time to make new roots before it falls over.

MERINGA PLOTS.

These plots are located on high ground, where they suffer consider-
ably from any continued drought. During the dry weather in March
signs of grubs began to appear on the edge of several of the plots, but
in no case has the yellowing extended farther into the plots. Indications
now are that the critical period is past, and that we will have a fair cut.
None of the injured cane has fallen, so with good rains it will all revive.

It is interesting to observe that the cane in the plot treated with
lime (CaO) at the rate of 1 ton per acre, has a beautiful dark-green
colour, and is the best of all the plots, though the soil in that part of the
field is rather poor, being on the highest ground. The meatworks manure
appears to be attractive to the grubs, because there is considerable
yellowing along the edge of this plot. On the other hand, meatworks
manure, mixed with white arsenic, placed in the drill after planting,
is showing good results. The cane is of good size, and shows little grub-—
injury, even where only 10 Ib. of arsenic was used per acre. In the plot
where 20 lb. of arsenic was used with 5 ewt. of meatworks manure per
acre, no signs of grubs have yet appeared. It is too early yet to draw
definite conclusions, but these indications are encouraging.

CANE GRUB INVESTIGATION, MAY, 1919.

The continued rains have wonderfully improved the appearance of
the cane in the infested areas. Fortunately there has been no heavy
wind, and in most eases the cane is still standing: Even where the leaves
became dry and brown new growth has started. Digging revealed new

42 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

roots beginning to shoot out: Apparently the grubs reached their zenith
about the middle of April, in this district, and they have now (10th May)
almost all gone down.

Mossman DIstTrRICT.

During the month I made a careful survey of the grub situation in
the Mossman district, a region which had been of special interest to me
because of the remarkable way the grub-pest disappeared there. In
former reports I have noted my observations on the emergence of the
cane-beetles, which were rather numerous last December, and I was
therefore agreeably surprised to find little evident injury from grubs
this season at Mossman.

I can only assign this immunity to two important factors :—Late
cultivation, and the use of ammonium sulphate. This chemical is used
rather generally throughout the district. The season, too, has been
particularly favourable for late cultivation, and I found absolutely no
injury to the late-planted cane. The only places where the grubs got
in their work, were in the ratoons and early-plant crops, which had been
laid by before the beetles flew. An interesting example of this was on
the farm of Crees Brothers. A field of 134 acres of Badila was planted
in June, 1918, on rich sandy-loam soil. Only about half of it was
cultivated during the flight of the beetles in December; the other half
was not worked at that time because of the difficulty in getting through
it. The crop is most remarkable, for the portion which did not get the
final cultivation has suffered considerably from grubs, while the worked
half is uninjured. The land was fallow for twelve months before
planting, because a crop had failed to strike. At the time of my visit
the late-cultivated portion was a beautiful dark-green, with stalks of
5 or 6 feet in length. Mr. Crees informed me that no manure was applied.
One could not find a better example of the value of cultivation in the
control of grubs.

The late-planted Badila in an adjoining block on this farm gave no
indications of grubs. It is about 10 feet high, and could not look finer.
About a bag of ammonia was used to the acre, after the rains began, and
cultivation was continued right through the flight of the beetles.

This farm formerly belonged to Mr. F. W. Barnard, who had serious
losses from grubs in the early days. He became an advocate of the use
of carbon bisulphide, and I found that he recognised the value of late
cultivation. He wrote:* ‘‘Farmers in this district, on land subject to
grubs, have found that by planting not earlier than September the cane
is young and growing vigorously at the time the grubs are about. The
plant is then continually throwing out fresh rootlets, which enables it to
withstand, to a certain extent, the onslaught of the pest. Also, at the time
the beetles lay their eggs cultivators are being freely used, which destroys
large numbers of them.’’

tae See Australian Sugar Journal,’’ Vol. 1, Dp. 481,

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 43

As is well known in the district, Mango Park, the estate of the late
J. D. Johnson, was once a centre of infestation. Mr. Johnson tried every
suggested remedy, and, finally, the worst fields were thrown out of
cultivation. I am therefore particularly interested in this estate, for it
is no longer a grubby centre. The infestation is very slight this season,
and only appears in one small field of ratoons, which received no ammonia
and only slight cultivation, which was finished before the beetles flew.

The crop throughout the estate is most promising this season, the
foliage is a beautiful dark-green, and since the recent rains the growth
has been most satisfactory. Only 123 acres are under cane, at present,
but a much larger area could be worked if facilities were available. The
present crop, which has been estimated at from 1,600 to 2,000 tons, could
well be doubled by increased planting and more intensive cultivation.

D1185 has been the principal crop on this estate, and at present
77 acres of ratoons are of this variety. This cane is very resistant to
drought, and, since most of the ratoons had a dressing of ammonia
during January, the impetus to the growth is most remarkable. The
application of this manure was followed by gentle rains, and the cane
got the full benefit.

The 46 acres of plant-cane was all put in late (August to Novem-
ber), and it is worthy of note that the cane has no sign of grubs, although
growing on the part of the farm which previously was always affected.
A part of this cane is on land which has been out of cultivation for seven
years, because it was considered too grubby for profitable working.

Most of the plant-cane has had a dressing of about 4 ewt. meatworks
manure per acre, and has made splendid growth, especially HQ 426
(Clark’s seedling), which seems especially suited to that class of soil.
It is double the size of the Badila, Goru, and D1135, planted at the same
time, and covers the ground so that it has no weeds, which are abundant
in the latter variety, because of its upright, sparse growth.

Present observations would indicate that it is possible to grow
bumper crops on even the worst infested locations by giving care to
cultural methods alone.

Infested portions must be planted late, so that the cultivation
coincides with the flight of the beetles, particular care being given to
forcing cultivation during the first three weeks after the beetles’ appear-
ance. Manure also has an important bearing thereon, especially the
nitrates, if applied at the time the cane is beginning to suffer from grubs.
Nitrates give the cane increased vigour, and forces new roots to replace
those that are eaten off.

Mr. W. P. Jones called my attention to one of his fields, which
demonstrates the value of intensive cultivation. He had the ground
ploughed eight times previous to planting in October. This cane is now a
very dense stand on the serub land, and is about 10 feet high. It has only
had about half a bag of ammonia per acre, but the colour is excellent.

44 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

Though this land was grubby in former years, there is now no sign of
injury, and there is every indication of a 50-ton crop. One can see why
Mr. Jones believes in thorough cultivation and the use of nitrate for
cane. It was on this estate (the late R. O. Jones’s) that such severe
injury usually resulted from the grubs. The only place where they
showed this season was along a ridge in a field of 4th ratoons, a part
of the field which had received no ammonia, but the injury was of no
consequence for the cane picked up again after the grubs ceased feeding,
about the middle of April.

There is a very interesting experiment in growing cane on the
black forest land at Saltwater, on the farm owned by Mr. C. A. S.
Andrews. This part of the farm has a most peculiar soil, as loose and
friable as a garden, and one would naturally conclude that it would
produce excellent crops. Experiments with early plantings, however,
have invariably come on well until the cane is about waist high, when
it quickly succumbs, as if the soil was too poor or dry. To investigate
this matter, last season I dug under dead stools in this class of soil and
found that Lepidiota french grubs were sufficiently abundant to account
for the failure. Hence I was especially interested to find that Mr.
Andrews was having success with late planting. He used both Clark’s
Seedling and D1135, and the cane has made most satisfactory growth in
spite of the severe setback that it got by the drought.

This land has been treated with 5 ewt. meatworks manure, and 14
ewt. sulphate of ammonia, per acre. This black soil is easy to work, for
it is free from weeds. No chipping was required, and the searifier was
used only two times; it is nevertheless very clean, and the cane covers
the ground.

The late planting in the present case has enabled the crop to escape
the grubs, and it is now too late for them to injure it. By eutting in
October or November it may be possible to ratoon the field so as to avoid
them again, if the horsework is continued through December. Moreover,
this pest, which has a two-year life eyele, probably will not continue
after this first lot gets out of the way. The frencha beetles appear to
prefer blady grass, and, as this is abundant on every side, they may stay
out of the ploughed land.

I was interested, too, in the disappearance of the cane rats at
Mossman. I could hardly find a trace of them on this trip. The mill
made no small outlay in laying poison baits at the end of crushing last
season. These were prepared with split canes and arsenic, and seattered
in all the rat-infested localities. Results were soon evident, for dead
rats were found, and there was a strong odour of carrion along several
of the watercourses. At any rate, the rats are not showing up this season,
and the prospects are very encouraging.

IMPORTANCE OF NECTAR-PRODUCING PLANTS IN CANE AREAS.
The observation of our native parasitic wasps (Campsomeris sp.)
feeding on flowers of various plants along the Mulgrave River suggested

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 45

that it would be wise to have more honey-bearing plants on the waste
ground near grub-infested cane areas, so that the wasps would be

attracted to these localities and eventually turn their attention to the
grubs.

It is well known that the adults of these parasites subsist upon sweet
secretions, which they secure largely from flowers, when these are to
be had ; they also feed upon honey-dew, and in breeding them in captivity
we found that they take any form of liquid sweet that is offered them.

As far back as 1901 Mr. J. C. Clarke,* of the Hambledon Sugar
Mill, Cairns, called attention to the importance of planting Congo or
pigeon pea (Cajanus indicus) around each field, and the growing of the
Bona Vista bean (Dolichos lablab) as a crop for green manure, so as to
encourage the multiphecation of parasitic insects which feed on the nectar.
He observed that the parasitic wasps were abundant at the flowers; and,
at the time of harvesting the cane, close by in the same field, he discovered
many of the larve of these parasites in the soil, where they were destroy-
ing the cane grubs.

In Mauritius, too, the interesting observation was made that Tiphia
parallela, which was introduced from Barbados, only reproduced success-
fully in localities where nectar-bearing flowers were present. In its
native home this species never was known to visit flowers, for it fed upon
the honey-dew from aphids. In Mauritius, however, plant lee are so
well controlled by natural enemies that the wasps were compelled to
turn their attention to flowers for existence.

These observations would suggest that our own native parasites of
the white grubs might be considerably assisted and encouraged if we
provided them with suitable nectar-bearing flowers in the vicinity of
the infested cane areas. Naturally, these wasps, in their quest for food,
are led far into the wild country, and, since they can easily find their
natural prey, white grubs, there under the grasses, they seldom return
to the cane areas to oviposit.

The abundant flowers of the pigeon pea are particularly attractive
to hymenopterous insects. Furthermore, this plant is of recognised value
for green manure,t a fact which was demonstrated by the experiments
of the C.S.R. Company years ago. They found that it was even better
than the black Mauritius bean, especially for the long fallow during the
dry months, for its dense foliage prevented the growth of grasses.

I secured a few seeds from Senator Crawford, who has a fine lot of
these bushes growing in his yard at Mossman. I shall try some experi-
ments as to their attractive value for the wasps by planting them along
the headlands of our infested fields.

* Agric. Gaz., N.S.W., 1902, pp. 1-6.
+ See Illustration, «Australian Sugar Journal,” Vol. 1, p. 21.

46 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

GREENHILLS ESTATE.

The immune area, which one sees upon entering the estate, is in
excellent conditions, both as to growth and colour. The late rains have
done much to retrieve the bad effects of the drought.

Even the infested portion of the estate is considerably improved over
what it was a month ago. Little of the injured cane has fallen, so, if the
rains continue, much of it will form new roots and revive, now that the
grubs have about completed their feeding.

It is interesting to note, again, the good appearance of the cane at
the edge of the fields bordering the feeding-trees to windward. In some
eases this shows no sign of infestation, the beetles apparently flying for
some distance, often several chains, before alighting to oviposit.

The October plant-cane of field J1 is still dark-green in marked
contrast to the brown fields on every side. There are only a few spots
which have shown any grub-injury, and these are rapidly improving.
J4, just across the tramline, planted in August, is a wreck. It had a lot
of cultivation, but none at the vital time—.e., during the early part of
December, when the beetles were beginning to oviposit.

It is also very satisfactory to be able to report the splendid condition
of the first ratoons in the west half of L6. The slight indication of grubs,
noticeable a month ago along the tramline, has entirely disappeared, and
the cane is in perfect condition. It will give a second good cut about
November, and will probably ratoon again successfully during December.

It will be unfortunate for our investigations if this estate is thrown
out of cultivation, as is now considered probable since the loss caused by
the grubs is so tremendous. One could not wish for a better growing-soil
if the grubs would let the cane alone. It is exceedingly friable and
fertile, producing satisfactory crops even without manures. In spite of
the fact, however, that I am more and more confident of success with this
type of land, I can hardly expect the present lessees to go on paying out
money, since they have already expended more than £26,000 above
receipts, on the chance that the estate would again produce a 30,000-ton
crop.

CANE GRUB INVESTIGATION, JUNE, 1919.

The past season has been particularly favourable for eradication
of cane grubs in most of the Northern districts. The dry weather early
in the year necessitated frequent cultivation, which not only hindered
ege-laying, but also is a most effective means of destroying the young
erubs. Then, too, the continued rains, which were so late in starting,
pushed the new roots just at the right time, when the beetles were getting
in their worst work; hence, in many eases, the cane was quick to recover.

During the month I made a survey of the grub situation on the
Johnstone River; and also secured a fresh supply of the borer-beetle
parasites from the Mossman. °

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 47

THE JOHNSTONE RIvER District.

I was interested to note the remarkable scarcity of grub-injury in
the Goondi area, for the beetles were particularly abundant last
December. The farm of Mr. R. Davis, which is typical of those at
Daraji, has always suffered considerably in former years, but there is no

*sign of grubs this season. It will be remembered that the Goondi Mill
was very late in starting last year because of the damage from the cyclone ;
hence all the cane was cut after September and the ratooning coincided
with the egg-laying of the beetles. Mr. Davis also planted late, so that
all of his crop came in for cultivation during the critical time, and his
crop is perfect.

I was also able to visit other farms through the kindness of the
Colonial Sugar Refining Company’s officials, and Mr. E. S. Smith, the
cane inspector at Goondi, took me to Stockton paddock, a grazing area
of 240 acres owned by Mr. Shaw. This is a most interesting spot, since
most of the money from the Cane Pest Destruction Fund is spent for
beetles collected there. Furthermore, strange to say, the surrounding
eane has not suffered from grub-injury. Mr. Shaw planted 30 acres
along one side of this paddock, and though this is adjoining feeding-
trees to windward, the first ratoon crop is in excellent condition.
Examination revealed numerous grubs in the grass-land ; hence, it appears
evident that all this extensive supply of beetles is developed there, and
they have not taken to the cultivated fields. If, however, all of this area
was cultivated, the ravages of the pest would probably appear.

At the South Johnstone Mill the scrub has only been felled along
the narrow valleys, so that naturally much of this cane area is affected
by grubs, for feeding-trees border most of the fields.

I was very fortunate in making the acquaintance of Mr. F. L.
Sugden, one of the most successful growers of the district ; a man untiring
in his efforts to improve the condition of his fellows, many of whom are
labouring under most distressing circumstances. Mr. Sugden’s own
success has evidently been due to his extensive experience along agricul-
tural lines and scientific application. Although his cane was seriously
troubled with grubs for several years, he has now practically rid his fields
of the pest. He uses lime in the cane holes on even the new land, and is
a firm believer in the value of conservation of humus. He also recognises
the value of removing the feeding-trees of the beetles; in fact, this
probably accounts for much of his present immunity. Another factor
which has an important bearing on this case is that Mr. Sugden controls
weeds in the cane of his stump-land by spraying them with sodium
arsenite. In this connection Mr. Sugden called my attention to a striking
demonstration of the value of spraying. On adjoining stump-fields one
grower removed the weeds by chipping, while his neighbour for the same
purpose used several sprayings of sodium arsenite. The full-grown
cane in both fields now shows a marked difference, although the land was
identical in every way. The chipped field is badly damaged by grubs,

48 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

while, right up to the line of treatment, the sprayed field is perfect. It
may be premature to form a definite conclusion, but the suggestion is
certainly worth consideration and further experiment.

ON THE VALUE oF LATE CULTIVATION.

Mr. Sugden also drew my attention to a 10-acre field of second
ratoons on his stump-land, and gave me the following interesting
history :—This cane was planted late in 1916. At the end of the season,
1917, half of the cane was cut and the balance left for plants. The
eyelone of March, 1918, wrecked this seed cane, but the best of it was
eut, and all the discarded decaying stalks were left on the ground. The
other half was so stunted by the cyclone that it made very poor growth,
and, later, accidentally was set on fire. Mr. Sugden then decided to
draw the logs together so that he could use the pony plough on this
part, and consequently cultivated during last December and January
while the beetles were flying.

The present result 1s most remarkable; the cane in the cultivated
area is as dark-green as if treated with sulphate of ammonia, and will
cut a splendid crop, contrasting sharply the half which was volunteered
through the rubbish, which is very yellow and grubby.

Evidently, the pony plough was effective in preventing the oviposit-
ing of the beetles, while possibly the surplus rubbish in the other part
was an inducement to the beetles to lay.

F'EEDING-TREES.

Through the kind assistance of Mr. Sugden I was able to visit
the extensive district extending out to Stewart Creek. The whole of this
area is new, but is subject to grub-attack, simply because of its proximity
to standing scrub. All of the holdings are small, and the owners are
working under extreme disadvantage, owing to lack of funds to clear
sufficient scrub to make their land immune. With the scrub quickly
cleared, I have no hesitation in saying that there would be little or no
danger from grub-injury, for the feeding-trees would then be left so
far back that the grubs could only damage the edges of the fields.

What I have said in regard to Stewart Creek district might apply
to other valleys supplying cane to this mill; for I observed on a trip to
the section known as the ‘‘Seventeen-mile,’’ that most of the small cane
areas surrounded by serub were considerably grub-infested, and that the
broad stretches of cane were immune, except, in some eases, if the fields
bordered the scrub.

It will be of interest to state that I do not find on the South John-
stone River the definite relation of infestation to the south-east trade
wind that I find in the Cairns district. Evidently the flight of the
beetles is considerably influenced as well by the land breeze from the
west, which is said to be the prevailing wind at night during the summer.
Hence we may justly conelude that in this district any near-by scrub is a

menace to the growing of sugar-cane.

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 49°

FurTHER NOTES ON THE VALUE OF ARSENIC FOR GRUBS.

Above I have alluded to the destruction of weeds by the use of
sodium arsenite. Indeed, I was considerably surprised to find that the
farmers, under the direction of Mr. Sugden, were so advanced in their
application of this valuable remedy. The Association has purchased and
is using most successfully the Vermorel knapsack spray for the eradica-
tion of weeds in new stump-land. Not only is the process much cheaper
and easier than chipping, but the effect of the arsenic will be far-reaching
in the soil for the control of root grubs.

I was very fortunate in being able to diseuss this important matter
with Mr. C. E. La Caze, a grower of extensive experience, not only
here, but also in Mauritius. About a dozen years ago Mr. La Caze was
farming on the Herbert River, and had serious losses from grubs. Often
half of his plant-cane was destroyed, and, he said, his losses amounted
to many thousands of tons on his three farms there. He was faced
with bankruptcy and decided upon extreme measures. Learning that,
white arsenic would destroy termites, he at once decided to try it for
the destruction of the grubs on all of his lands. He hit upon the plan
of mixing the arsenic with meatworks manure and arranged to have
the mixing done at the meatworks. As arsenic was then cheap he used
14 Ib. of the poison for each ewt. of the meatworks manure, and applied
about 5 ewt. of the manure to the acre, placing it in the drill before
planting. Between 500 and 600 acres were treated in this way. The
results were immediately noticeable, and, he informs me, there have
been no further grubs on that land since.

This information certainly is very interesting, and appears to be
conclusive, but Mr. La Caze said that he kept no checks, and also stated
that some of the feeding-trees were being removed at about that time,
so it will be well to try similar experiments with arsenic in other places
before we can decide definitely that the poison was the eradicating factor.

I wish to urge the importance of trying an experiment with arsenic
on every grub-infested farm. I do this largely as a result of our success.
with this remedy at Meringa, where we got excellent results by using
only 20 lb. of the poison to the acre, mixing it with about 5 ewt. of meat-
works manure, which was applied in the drill at the time of planting.

I would suggest that each grower try at least 1 acre, leaving an
area alongside as a check. The poison may be applied either alone or
mixed with the meatworks manure; but I think it important to centralise
the poison by placing it in the drill. I have advised many growers on
stump-land to test its value by using 20 Ib. of the poison per acre,
applying it in the cane holes after the plants are covered. In the case
of ratoons among the stumps, the dry arsenic might be dusted on the
trash after cutting, placing most of it in the centres. This could be
done easily by placing the poison in two bags of thin hessian, attached
at the ends of a pole about 5 feet in length. Holding this by the middle it
is an easy matter to dust two centres at a time by walking over the row-

D

50 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS.

After dusting, the trash should be relieved slightly, thus bringing the
arsenic largely into the middles of the trash piles, where the grubs are
sure to reach it as it combines with the decaying organic matter. Asa
matter of course the ovipositing beetles will seek these piles of rubbish,
and the young grubs may get their death-blow before the advent of the
dry weather, at which time they usually attack the cane roots.

It will be of interest to users of arsenic to know that soreness
developed on hands and other parts of the body can be quickly cured by
bathing the affected parts in a solution of hypo (hyposulphite of soda).
This I learned years ago when | was using the poison constantly.

NECTAR-BEARING EK LOWERS FOR PARASITES OF WHITE GRUBS.

Last month I ealled attention to the importance of this subject,
hence I was considerably interested when I found these beneficent
insects in great numbers in the flower garden at Mr. Sugden’s farm,
which, by the way, is the finest display of colour I have recently seen.
Most canegrowers consider their time too occupied for the growing of
flowers, but the trouble of gardening will probably be proved to pay in
more ways than one. Both sexes of the wasp Campsomeris tasmamensis
were very busy in the garden on sunny mornings, especially on the
flowers of the Klondike cosmos and pigeon pea.

It is not improbable that these insects have assisted materially in
eradicating the grubs which formerly troubled these fields.

Mossman District.

The Beetle Borer, though practically wiped out in most parts of
the district by the tachinid parasite (Ceromasia sphenopheri), has
become somewhat troublesome in one field on the farm of Crees Brothers.
This is the location where I secured the parasites last year, and both
parasites and borers have multipled there because the cane was simply
volunteered without burning the trash.

Fully 90 per cent. of the borer-beetles’ grubs are parasitised. The
only grubs which escape the flies are those down in the butts of the
stalks, where the flies find difficulty in reaching them.

It is interesting to note that a large proportion (more than half)
of the flies had already escaped from the puparia. Therefore it would
appear best to collect these infested stalks earlier in the season, say, about
April, for cane planted late in August, or when the cane is about eight
months old.

For the control of this borer-beetle it is decidedly best to burn the
trash, for then practically all the grubs succumb, even when inside the
discarded sticks on the ground. The flies, on the other hand, are more
apt to escape to other fields if the burning is done after cutting the cane
green. This I found to be the case in the mill nursery, where we first
secured the parasites. Here the trash was burned off after cutting, and
I was unable to find a single live grub in the blackened stalks. This cane

MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 51

had not been burned for several years, and the borers and their parasite
were well established. Now I find that there is scarcely any borer-injury,
and the few grubs I was able to locate were fully parasitised. Evidently
the flies are able to take care of themselves when the trash is fired.

The parasites secured on this trip are to be liberated in the Mulgrave
and Babinda districts, where the beetle-borers are still giving consider-
able trouble, especially on the low-lying fields. There has been a very
evident spread of the pest during the past year, because of the lack of
care in selecting seed. The parasites that we formerly liberated in these
districts may possibly be established, but it is a difficult matter to
discover them until the cane is cut. Once they get a start, however, they
ought to quickly spread to most of the infested fields.

By Authority: ANTHONY JAMES CUMMING, Government Printer, Brisbane.

aay rs a
’ : : 3 2 5 LS # ( at i. ny
: Pan A" ais ae aA Why
: é ? al
Fyn) AUST Ce AA OE Se ia 19 wh ait) Wai ane iy ts ae J

' /

a. rT a hee Praga 4 Cn Gin Vib Tepe a, } aay Sits
a baie tia y Wit yf Ada t : Negi ;
4 a fi vt aketh oy ie ies ois +o care) as Fey has Men
dh a} ‘Has 1 pee Vibe Peay) ase it Sh")
Ny ie \ fe. Las Py Ba ot cs
bh ara at, sie fie ee
+a ual eS rt tae Ly ae Ta ee May
—t aa ee vy, a, ‘i a 3 r r
yee i PN OS ea ii ee abort ale > ‘oe ON i Talis! re
on (OL) Geman t anid ch Wii pe
D " TN it ¥y ° aes “ean re Sea
an a ee 4 rth way vei ae in Ast i |
OF “it, Sere
Ni - are sates ed oh wht Re Ri ee ay on te i
ir ev Aiton Peau vai bie bulAt DS i i a in
ei i. ie a or, te ry é fete tovaes

aatmy a tam! WSs

y we
“iv pe ALN

ia

ALLA