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it is easily washed away by showers and being not easily seen 
when used alone, is difficult to apply evenly over the surface of 
the plant. On the other hand, the arsenate of lead is entirely 
insoluble in water, thus obviating any danger of burning the 
foliage; it is white in color, thus insuring an even coating over 
the plant, and is quite adhesive, not being easily washed away by 
showers. These properties of the arsenate of lead in the freshly 
prepared wet form make it preferable to the less adhesive, though 
more active Paris green. The arsenate of lead is now in the mar- 
ket in paste form, ready for immediate use. Such preparations 
are for sale in Honolulu. 
Since those insects feeding upon the juices and sap of plants 
do not swallow portions of the plant itself but gain their food 
by inserting the beak or proboscis through the epidermal layers 
into the tissues, it is to be seen that they would not be affected 
by a poison placed on the surface. Therefore, in fighting the 
insects belonging to this second class, other methods must be 
employed. The methods are to kill the pests by applying to their 
bodies an external irritant or contact poison, and by submitting 
them to the fumes of some deadly gas or fumigation. In the 
case of the external irritants applied as a spray or powder, the 
entire body of the insect must be covered and every infested por- 
tion of the plant treated to have the work effective. The oil 
sprays or washes are the most important remedy for sucking 
insects and the standard one has been the kerosene emulsion. The 
resin wash is not suited to the Hawaiian conditions because of 
the fact that this wash acts principally as a covering to the insect 
and kills by smothering the pest. Resin wash has been used with 
success against certain scale insects in California during the rain- 
less season. With the frequent rains here and the necessarily 
greater length of time for the resin wash to act in comparison to 
the oil washes, the more active kerosene emulsion should be used. 
Insecticides are applied to plants in liquid form or as a powder 
in dust form. The most common method is a liquid in the form 
of a spray. There are many manufacturers who make pumps 
and spraying accessories expressly for this purpose. The appara- 
tus ranges all the way from a hand syringe with a capacity of a 
few ounces to a steam or gasoline outfit holding several barrels. 
The important parts of any spraying device are the pump to force 
the liquid out through a hose and a nozzle at the end of the hose 
to convert the liquid into a spray. Where the plants are any 
height, trees for example, the spray must be brought in close 
proximity to the parts of the plant to be treated, since a spray 
will not carry any distance. This is done by means of an exten- 
sion rod. 
Successful spraying depends mainly upon five things : ( i ) 
Understanding the feeding habits of the insect pest, that is, 
whether it is a biting or a sucking insect; (2) the nature of the 
remedy to be applied; (3) the proper preparation of the spraying 
