86 
SOME INSECTS INJURIOUS TO TRUCK CROPS. 
soap and 1 gallon of kerosene to 25 gallons of water; resin, 1 pound 
to 16 gallons of water ; and black leaf tobacco extract, 1 gallon to 65 
gallons of water. Of these Mr. Quayle says that the last seemed most 
effective, with kerosene emulsion next, and that none of these sprays 
in the given proportion injured the foliage at all. 
It is entirely possible to kill most of the beetles well bit by the spray, but 
many escape between clods in the soil or are protected by the vine or are con- 
cealed in tbe growing tip. The percentage killed, however, will be satisfactory, 
but this [treatment] must be repeated so often that the operation becomes 
laborious and costly. 
While kerosene emulsion and whale-oil soap are practically never 
advised as standard remedies for mandibulate or chewing insects, 
Fig. 18. — A crew spraying hops in British Columbia. (Original.) 
such as this flea-beetle, both are employed in the infested terri- 
tory against the hop aphis, or " louse," and therefore the hop grower 
is familiar with their preparation and use. It has been ascertained 
that when these are used against the hop aphis the flea-beetles coming 
into contact with the emulsion are killed. The probabilities are that 
kerosene emulsion properly prepared and applied in the affected 
regions will be considerably less expensive than a tobacco extract, and 
it is possible to make a tobacco extract which would be comparatively 
cheap. In recent experiments made under the writer's direction at 
Norfolk, Va., whale-oil soap, used at the rate of about 1 pound to 10 
gallons of water, employed against aphides, has proved quite as ef- 
fective and as economical as kerosene emulsion, considering the fact 
