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watering hose will be sufficient to entirely replace the spray pump. 
The arsenites may be used in the same way as kerosene, using a 
mixture stronger than the standard and allowing it to be diluted in pass- 
ing through the nozzle. A stopcock on the inlet tube will graduate 
the proportions, as with kerosene. Perhaps an apology is due the Asso- 
ciation for presenting this suggestion before I have actually proved its 
utility. I am now having nozzles made for experiment, and will be 
able to give a definite report later. 
Mr. Smith asked if others had had experience with the combination 
pump which was being put on the market by the Deming Company, 
and said that his experience with it had not been satisfactory. 
Mr. Marlatt said that in his paper, which was to follow, some experi- 
ments with this pump were detailed which would answer the question 
of Mr. Smith. 
Mr. Marlatt then read the following paper: 
NOTES ON INSECTICIDES. 
By C. L. Marlatt, Washington, D. C. 
So much has been written about insecticides in the publications of the 
various experiment stations and those of our Entomological Division at 
Washington, and they have so frequently been a subject of discussion 
at the meetings of this Society, that one might infer that enough experi- 
ence had been accumulated and information gained to enable us to 
arrive at definite conclusions in the use of the more important insecti- 
cides against the leading injurious insects. It must, however, be 
strongly impressed on every member of the Society who is engaged to 
any extent in personal experimentation and actual field operations 
against insects that the subject is still far from being exhausted, and 
that every season's experience develops a host of new facts and 
methods of greater or less value. It is not sufficient to know that ker- 
osene emulsion or resin wash will destroy certain classes of insects or 
insects in certain stages of development, and that they are not gener- 
ally injurious to foliage, but it is necessary to know also the minute 
particulars of time, weather conditions, and conditions of the insect 
which will most conduce to successful treatment. As an illustration 
of this, the various scale insects which have always been leading pests 
in subtropical regions, and are rapidly gaining importance also in the 
north, are, generally speaking, invulnerable to insecticide action in any 
strength which may be safely applied during the growing season alter 
the covering scales are once well formed; and these insects can, there- 
fore, only be successfully treated immediately after the young are dis- 
closed. The farmer or fruit-grower, without the aid of a hand lens, can 
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