336 Report oF THE ENTOMOLOGISTS OF THE 
DIAGRAM OF PLATS IN 1897. 

~ 
Dates of Plat I. Plat Il. 
spraying. 

June 3. | Green arsenite and whale oil ; Green arsenite and whale oil 
soap. soap. 
19.54-Same’2. 7 ot Gira teeta seo Untreated. 
Bde | AME 2 vis fee PRS er § Untreated. 
Results ...| Marketable willows, 2 tons. | Marketable willows, 1 ton. 

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Results in 1897.— Comparatively few beetles came from neigh- 
boring fields and hence the results were more satisfactory than 
in 1896. As shown in the diagram the yield of the half acre 
which was sprayed three times was twice that of the half acre 
sprayed but once. 
The results of spraying alone as a means of combating. the 
beetles, compared with depending entirely upon the machines for 
catching the insects, may be shown by comparing Plat I to a 
near-by field upon which the machines alone were used. The 
conditions were practically the same in both cases and the yield 
was about the same but there was a decided difference in the. 
cost of treatment. In the field referred to, a machine was kept 
running a part of every day for nearly three weeks, which is not 
exceptional, at a cost of $4.05 per acre for labor while the cost of 
spraying, with a power sprayer covering six rows, was but $2.58 
per acre for labor and materials for the three applications. Thus 
the expense of spraying was but little compared to the yield and 
much less than the. cost of running the machines long enough to 
produce the same results.’ | 
TIn the field referred to the machines were used but once a day through- 
out the entire three weeks. Usually it is necessary to go over the fields 
twice a day for a week or ten days, thus incr easing the expense. 
