259 
nomically destroyed when in the larval state, others when adult 
In many cases handpicking is the most economical method m 
the end, especially in the case of leaf-feeding caterpillais when 
present in abundance, but poisonous substances cam at tunes be 
used successfully. These are especially valuable in the case of 
Blights ( Coccidce ), green fly, etc. The best are tuba-root, to- 
bacco phenyl, kerosine and soft soap and sulphide of potash, 
London purple and Paris green are extensively used as insecti- 
cides in some parts of the world, but I have not found the former 
at least very successful here. It is purple powder insoluble in 
water but it is generally used mixed with water for convenience. 
On the grubs of the coco-nut beetle I found it had practically no 
effect either dry or in water, the grubs burrowing about in the 
powder quite unharmed, nor was it more successful in the case 
of the bee-liawk caterpillars, though the younger ones were killed 
bv being wetted with a mixture of London purple and water, the 
larger ones soon recovered. It is however useful against termites 
either sprinkled in holes for posts, or painted on the wood work 
in the form of a mixture with kerosine. In this way it can be 
used against the house termite ( Calotermes domeshca). It must 
be remembered that, as London purple and Pans green are pre- 
parations of arsenic, they must not be used on rnuits or 
vegetables intended for food. Sulphide ot potash in solution 
seems to be more deadly to caterpillars and is not at all injuri- 
ous to Plants, but rather acts as a manure. Tuba root (Dcrns 
elliUica ) is pounded and soaked in water, making a soapy mix- 
ture which is deadly to many insects, especially caterpillars and 
blights Phenyl is useful for blights and especially those white 
Coccidse which are protected by a coating of wax which thiows 
off the insecticide liquid, but which is partly dissolved by 
Phenyl which is then fatal to the insect. Phenyl is a tarry look- 
ing liquid which, when mixed with water, resembles milk. It 
should be stirred with water till it is of the colour of good milk, 
used thus it has no bad effect on even delicate leaves. For to- 
bacco water, the ordinary Javanese tobacco can be used soaked 
in water. It can be improved by the addition of soft soap which 
causes it to adhere better to the leaves. Kerosine and soap is 
olsn a good mixture for blights. . 
These liquid insecticides can be sprinkled from watering cans 
or syringes, or a spraying machine of which many kinds have 
been invented, can be used. For a large area the latter is the 
most suitable. The great amount of rainfall militates against 
liquid insecticides as a heavy shower is apt to wash it away be- 
fore it has taken full effect. , , ^ 
The best work on insecticides is Lodemans Spraying o 
nlnnts ” (Rural Science Series). 
P Smoking the trees with sulphur or burning rubbish requires a 
good deal of care or the trees may be damaged. Small pots of 
sulohur on poles held near bushes will often clear off caterpillar 
and has been used successfully, it is said in Java, but fumes o 
sulphur, if prolonged, are apt to damage the foliage. 
