Oct. 1, 1899.] THE TEOPICAL AGRICULTURIST. 
231 
REMEDIAL MEASURES AND 
INSECTICIDES. 
ByE.E. Gbeen, Goveenment Entomologist. 
In the following pages I have endeavoured to briug 
together scattered information on the various methods 
that have been employed in dealing with insect pests 
of the family Coccidw. Though such treatment may 
in many cases be found suitable to insect pests of 
other families, I do not propose to give here a 
general treatise on insecticides, but to confine myself 
to measures applicable to the subject of the pre- 
sent work. 
Little or no originality can be claimed for the 
following remarks. They are very largely compiled 
from the published work of trained entomologists 
(chiefly American) in difierent parts of the world. 
America has long been in the forefront in the prac- 
tical application of economic entomology. 
Bemedial measures may be discussed under two 
main headings : Prevention and Cure. The former, 
being by far the more important, will be' dealt 
with first :— 
Preventive Measures. 
Of first importance amongst preventive measures, 
I would place Quarantine Regulations. It is a fact, 
repeatedly demonstrated, that imported pests, are 
the most serious. An insect may attract little or 
no attention in its original home, where it is kept 
in check by its own natural enemies, a system re- 
cognised as 'the Balance of Nature.' But take it 
away from its home ; place it in a congenial climate 
with an ample supply of suitable food, and it will 
multiply without the checks that have prevented its 
increase in its original habitat. The, very fact of 
extensive damage by any insect ma.y of itself almost 
be accepted as proof of its foreign origin. Looking 
through the list of the difierent scale-insects occuring 
in Ceylon, I find that all the more troublesome 
species have been previously described from some 
other country, and are, therefore, presumably im- 
ported insects. The home of the ' Lantana bug ' 
(Orthezia insignis) is now supposed to be some-where 
in S. America ; and there is evidence in favour of 
the supposition that we owe our ' green coffee bug ' 
(Lecanium viride) to Western Africa, Aspidiotus 
cydonice, Chionaspis liclavis, and Mijtilaspis citricola 
were originally described from America. Aspidiotus 
camellice, A. cyanophylU, Cliionasjns aspidistra:, and 
Dactylopius ciiri, are all well known on the conti- 
nent of Europe. Aspiodotua aurantii and Pul'oinaria 
psidii have their home in Australia. Our former 
coffee pest, the 'brown bug' ( Lecanium cojf eon ) might 
perhaps be quoted as an exception to this rule, as 
it was first recorded from Ceylon. But this insect 
is now considered to bo merely a local variety of 
Lecanium hemisphcericuni, an insect found all over 
the world, and whose origin is uncertain. On the 
other hand, not a single undoubtedly native species 
has attracted any notice as an insect pest in Ceylon. 
We have only to recognise these facts to appre- 
ciate the importance of a properly conducted system 
of quarantine for all imported plants and fruit. Our 
insular position in Ceylon, with but one main port 
of entry, gives us a peculiar advantage in carrying 
out such a system. A single quarantine station, with 
a single fumigatorium, will be snfflcient in our case 
to deal with the whole importations of the island. 
It is true that, in spite of quarantine regulations, 
particular pests have found their way into protected 
countries. In such cases failure must be attributed 
to incompleteness of execution. And, though some 
few pests may have evaded all precautions, how 
many others must have been refused entry ? The 
records of existing quarantine establishments give 
long lists of dangerous insects detected on arrival, 
and destroyed before they have had the chance of 
obtaining a footing in the new country. I believe 
it is the custom at most qusirantme stations to 
examine imported plants and fruit, and if they 
(i^joeor to be free tx<)m bUgbtsi t9 pass ^hem with- 
SO 
out treatment. But I maintain that not even the 
most experienced entomologist could guarantee a plant 
as absolutely free from insect life. Minute larvse 
and eggs may luik beneath bud-pcales, in the axils 
of leaves, or in unnoticed crevices of the bark. To 
be really effective, quarantine must be complete. 
Every live plant and fresh fruit should be subjected 
to treatment, whether it appear to he free from dis- 
ease or not. 
The only sure way of reaching every hidden in- 
sect is by fumigation. If properly conducted, there 
is little danger of permanent injury to the plant. 
Even though some few delicate plants may be injnred, 
or actually killed by the process, this is a very 
small consideration in comparison with the damage 
that may be effected by a single imported nest. What, 
for instance, must have been the pecuniary loss to 
the colony from the ravages of the 'green bug'— 
a loss that, in all probability, might have beeu pre- 
vented. And compare this loss with the value of 
all the delicate plants that have ever been imported 
into Ceylon ! But, for such tender plants, it is 
possible to employ other treatment than is recom- 
mended for hardy shrubs and trees. 
_ For wholesale fumigation of plants and fruit their 
IS nothing to equal hydrocyanic acid gas, generated 
by rnixing cyanide of potassium, water, and sul- 
phuric acid in certain proportious. This treaament 
IS cheap and effectual. The gas is of the most deadly 
nature, and will penetrate every crack and crevice, 
and do its work thoroughly. The application is quite 
simple. All that is required is a close-fitting chamber, 
provided with a flue for the escape of the gas after 
the operation. The more air-tight the chamber, the 
more complete will be the work. It should be fitted 
witn racks to receive removable travs, upon which 
fruit may be spread. The objects to be fumigated 
are placed into position ; the chemicals are mixed 
in leaden or earthenware pan and placed on the 
floor, the door shut, and the room kept closed for 
from half to three-quarters of an hour. The flue is 
then opened, and, after a sufficient time (about half 
an hour) has been allowed for ventilation, the door 
is unlocked, and the plants, &c., removed. It is 
not advisable to take the subjected plants directly 
into the open air if the sun is shining. They should 
be kept for a few hours under shade, which will 
greatly lesson any danger of damage. 
Mr. C. P Lounsbury, official Entomologist at Cape 
Town, has kindly supplied me with full particulars 
ot the work of the Fumigatorium at that place. From 
his letters and reports I have extracted the follow- 
ing directions and suggestions : — 
For each 300 cubic feet of space enclosed f and in 
proportion for greater and smaller spaces^ 1 ounce 
of 98 per cent, potassium cyanide, 1 ounce of sul- 
phuric acid, and 2 ounces of water will be required 
to generate gas of sufficient strength to kill the 
insects. Double this strength, or the same amount 
of meterials to 150 cubic feet enclosed, may be used 
upon woody plants without danger of seriously in- 
juving them. The greater strength should be em- 
ployed whenever practicable, as it will ensure the 
death of the eggs as well as the active insects. 
Imported plants are usually in a more or leas 
dormant condition, which lessens danger of iniurv 
Mr. Lounsbury writes, in his Beport of June 1897 
'Injury to the tips of new growth generally results' 
This injury is in no wise serious, and is quickly 
outgrown. The operators consider it a favourable 
indication, as when such injury results it is quite 
certain that the gas has been present in sufficient 
strength to destroy all of the insects.' 
With respect to fruit, I again quote from Mr. Louns- 
bury s letter : 'I had lemons and oranges analysed 
after treatment, and found that after a few hours 
not more than a trace of the gas remained in the 
rind. There is much more natural cyanogen in a 
single seed (so the analyst told me) than what re- 
mains m the fruit from fumigation. We have no 
