14 The: Colorado Experiment Station 
oilcloth or tin extending to within two inches of the bottom of 
the machine, the floor of which is extended forward about four 
inches in front of the shield. A two-by-four extends outward 
from either end to the distance of four feet and to this is attached 
the single-tree. An inverted V-shaped tin is fastened to the front 
end of the extended floor, the back part of the V being free and 
slightly curved upward and extending under the base of the 
shield. In operation, this tin shakes up and down, and the hop¬ 
pers jumping up strike the curved shield, slide down to the in¬ 
verted V front, and, being unable to obtain a foothold, pass down 
and under the main shield and into the box. 
This machine operates in the same manner as the hopper doz¬ 
er, with the exception that the hoppers must be killed before the 
machine is unloaded. This may easily be accomplished by spray¬ 
ing them with kerosene. 
The “Live Hopper Machine,” showing concave shield front and in¬ 
verted “V” at the base. These machines were used on rough areas in the 
grasshopper campaign, 1916, San Luis Valley. (Original). 
INSECTICIDES 
Insecticides used in hopper control may be grouped under 
two heads, those which kill by contact, such as kerosene, kerosene 
emulsion, etc., and those which act upon the digestive tract. The 
latter may be applied by means of spraying the poison directly 
upon the foliage which the hoppers will feed upon, or by mixing it 
with bran or other material in the form of a mash. 
Poisonous Sprays .—Poisoning vegetation with arsenical 
sprays is often practical in areas where the young hoppers are 
