13 
ive. So far as the writer knows, however, this has never been given 
a thorough trial for the potato beetle. It should be tested. 
Fall and spring plowing are of value in a general way, as for 
other insects which pass the winter in the earth, but they are by 
no means perfect measures, as the beetles are hardy and not much 
affected by this treatment. 
ARSENICALS, 
Arsenicals are the best remedies for the Colorado potato beetle, 
and on small potato patches Paris green is usually applied dry, mixed 
with flour; but, as previously stated, it is best used as a spray. 
Where early hand methods have been employed, thorough treatment 
with an arsenical should follow. 
Paris green, dry.—When applied dry, Paris green is mixed with 
from 10 to 20 parts of cheap dry flour, sifted land plaster, or fresh 
air-slaked lime. This remedy affords best results early in the sea- 
son on young plants. It should be dusted on preferably when the ' 
dew is on and by means of powder guns or bellows, or the so-called 
“ dust-spray ” machines, so as to cover the plants and leave as little 
surface as possible for food for the first-appearing beetles. In spite 
of this, however, some beetles will succeed in depositing their eggs on 
the lower surface, which is difficult to reach with a dry mixture, and 
when the larve hatch another application must be made. In fact this 
remedy must be used for some time or until the plants obtain a fair 
growth, when spraying will be found more effective. 
The Paris green spray is prepared by mixing the arsenical with 
water or Bordeaux mixture“ at the rate of 1 pound of poison to 75 
to 125 gallons of the diluent. If water alone is used, quicklime 
in about the same proportion as -the poison should be added to 
prevent scorching. For the proper mixing and application of this 
spray a bucket pump or knapsack sprayer of good quality is sufli- 
cient for use in small gardens, but on a larger scale a potato sprayer 
to be drawn by one or two horses through the rows of plants is 
necessary. With the latter, from two to six rows can be treated at 
2 time. Special four and six row potato sprayers are on the market. 
The Paris green should be mixed with a small quantity of water into 
a thin paste before the bulk of water is added and should then be 
thoroughly blended by churning in the force pump or sprayer. The 
mixture, being a mechanical one, is not constant, and the Paris green 
will sink to the bottom. To avoid this it must be stirred constantly 
while being applied. It is advisable to use the Bordeaux mixture as a 
diluent. as this is a valuable insect repellent as well as a standard 
a Directions for the preparation of this fungicide and the arsenicals here dis- 
cussed are given in Farmers’ Bulletin 127, U. 8. Department of Agriculture, 
which can be obtained on application to this office. 
[Cir. 87] 
