REMEDIAL MEASURES: HOPPERDOZERS. 37 
dently on account of the quite recent burning and the fact that 
unfavorable weather had kept the hoppers so inactive that there had 
been little migration from unburnt to burnt portions. With so 
positive a case as this along with many others of nearly equal certainty 
it seems entirely warranted to recommend burning for such pasture 
lands and range as can be- treated in this manner without detriment 
in other ways. 
CAPTURING IX HOPPERDOZERS OR TAR PANS. 
The direct treatment which has had the most thorough trial is the 
use of the hopperdozer, which consists of a sheet-iron strip coated 
with coal tar. The apparatus is drawn over the grass and the insects, 
hopping at its approach, fall upon the surface and thus many of 
them are killed. In a number of tests of this method at the Iowa 
Agricultural Experiment Station it was found that, in pastures ordi- 
narily infested with leafhoppers, the insects could be captured at 
the rate of a half million to a million to the acre, which very apprecia- 
bly reduced the number occurring in the treated fields. Probably 
three-fourths or more of the hoppers occurring in any particular 
area were captured by one or two treatments of this kind. It was 
found that this treatment could be applied to best advantage during 
the latter part of the afternoon on sunny days, when the insects 
would jump with the greatest facility and could be caught in the 
greatest numbers. In one experiment with tins plan, two equal areas 
were treated for a season, and a comparison of the hay for the area 
showed an increase for the treated plat of more than 50 per cent. 
Two lots of bluegrass were used in an experiment, each containing 
about one and three-fourths acres. These were fenced. One plat 
was treated, leafhoppers being collected from it in large numbers at 
various times, and upon this plat cattle, varying in numbers, had 
been pastured at different times throughout the season for a period 
of about 73 days. On the other, untreated, a single cow was pas- 
tured. A comparison of the number of animals on each plat, taking 
into account their relation with the plat and the time during which 
they were pastured upon the area, shows that the treatment gave a 
gain of 68 per cent in the capacity of the pasturage. While this 
test may not be taken as an exact measure of the advantage to be 
gained in other cases, it should stand as an approximate gain for 
that test. However, it is evident that migration of these insects 
from adjacent areas would tend to reduce the advantage of the treat- 
ment, especially in a smaU tract, and that the greatest advantage 
could be secured from treating an entire pasture, so that there would 
be no opportunity for reinfestation from adjacent lands. The 
expense of this method of treatment is not great, it being estimated 
that in a section suitable for farm operations it may be easily per- 
formed at a cost of 7 cents per acre. 
