KEMEDIAL MEASURES AND CONCLUSIONS. 49 
Oil barriers. — If the weather should be wet, or if light showers 
should occur, so that it is not possible to keep the surface of a dust 
barrier pulverized and dusty, the farmer may resort to the oil barrier. 
The type of the oil barrier used in past campaigns against chinch 
bugs is the earth ridge, with a small line of coal tar on top. It has 
been thoroughly tested, and if properly maintained will prove effec- 
tive as a means of trapping and destroying the bugs in large quan- 
tities. 
The plan found most effective is that of turning a double furrow 
with a plow, and thus forming a ridge, and putting tar, etc., on top 
of this ridge. On the side of the ridge next to the small grain, 
postholes about 75 or 100 feet apart and 2 feet deep are dug. The 
bugs are thus retarded in their march by the ridge, and, being re- 
pelled by the tar, etc., swarm along the ridge and crowd each other 
into the postholes. When the holes are nearly filled with bugs dirt 
should be thrown in and tramped down, and new holes dug to take 
their places. 
After the ridge is thrown up by the plow the top should be 
smoothed off and packed down so as to hold the tar or oil which is 
poured thereon. The sides of the furrow should also be smoothed 
so as to make it difficult for the bugs to climb up. This can be done 
with a hoe and a rake, but it is much more quickly done by using a 
drag made with a concave bottom of the form of the desired ridge. 
This should be heavily weighted and drawn by horses along on top 
of the ridge. Such a drag is easily constructed and will save much 
time and do better work than can be done with the hoe and rake. 
The bottom of the drag will scour better if covered with sheet zinc. 
Coal tar as it comes from the gas works is the best thing known 
for this type of barrier, as it does not sink into the ground readily 
and is very effective against the bugs. No. 18 heavy residium asphal- 
tum from the oil refinery was tried as a substitute for the tar in one of 
our experiments conducted during the past season and gave excellent 
results. It stands next to coal tar in its efficiency, and costs about 
the same. It could be procured at the refinery last summer at $4 a 
barrel. It will require about one barrel of the tar or asphaltum for 
every 80 rods of barrier constructed. Crude oil was also tried, and 
while it was effective for a time after being applied, it soaked into 
the ground very readily and had to be renewed frequently. If crude 
oil is used, about twice the amount given for the coal tar will be 
needed. The cost of crude oil at the refinery (including barrel) was 
$1 in 1910. 
Whichever one of the above repellents is used, it may be applied 
by using an old teakettle, coffeepot, or sprinkler with the perfo- 
rated end of the spout removed. In applying the tar or asphaltum 
