Fifth Annual Report. 45 
Various methods of accomplishing this have been in vogue for 
many years. 
As soon as it was seen that infectious diseases would probably 
not always be efficient in destroying the chinch-bugs in sufficient 
numbers to save the crops, our assistant, Mr. Marcy, turned his 
attention to coal-tar, petroleum and salt as barriers to keep the 
bugs from entering the corn-fields.. The plan found most effect- 
ive was that of turning a double furrow with a plow and thus 
forming a ridge, and putting the tar, etc., on top of this ridge. 
On the side of the ridge next to the small grain, post-holes 
were dug broadening toward the bottom, about 100 feet apart. . 
The bugs were retarded in their march by the ridge, and being 
repelled by the tar, etc., would swarm along the ridge, and in 
so doing would crowd each other into the post-holes. In some 
cases, when the holes were nearly filled with bugs, dirt was 
thrown in and packed down; in others a little petroleum was, 
poured. Both methods were effective in killing the bugs. It 
was found that where the holes were deep the bugs died with- 
out any special effort to destroy them. 
After the ridges are thrown by the plow it is best to smooth 
and pack down the top and sides somewhat, in order to keep 
the tar, etc., from sinking in deeply and to protect the ridge 
from too great washing away by rains. This process was neces- 
sarily slow and tedious by hand, and to obviate this a drag with 
a concave bottom of the form of the ridge was made, and when 
weighted with rocks or dirt and drawn by horses over the ridge 
it did very effective service, saving a vast amount of time and 
doing the work better than could be done by hand. The bot- 
tom of the drag was found to scour much better when covered 
with sheet zinc. 
Coal-tar as it comes from the gas-works, crude petroleum ase= 
taken from the oil-well and kerosene oil mixed with salt were used 
on the ridges. These substances are offensive to the bugs, and 
they seldom attempt to cross them or even to come close enough 
to touch them, but on approaching these offensive substances 
the bugs turn and run along the ridge in the evident hope of 
finding a gap through which they may pass. 
Coal-tar is the best of the substances named in that it stands 
on the surface better and is not so readily washed away by 
rains. However, crude petroleum and kerosene are very effi- 
