60 THE CHINCH BUG. 
at the trapnole, but both of these plans were afterwards regarded as 
unnecessary, a single straight line being entirely sufficient and less 
expensive. The numerous cases where these methods were put into 
execution with entire success and at small expense is the best possi- 
ble proof of their practical utility. If a farmer is situated near town, 
where refuse tin cans are dumped in any locality where they can be 
got out of the way, he can select the larger of these, set them in the 
post holes and partly fill them with kerosene and water. The water 
being heavier than the kerosene will sink to the bottom, leaving a 
stratum of kerosene on the surface. The chinch bugs falling into this 
will be forced down by the weight of those coming after, and thus all 
will be passed through the kerosene into the water below. This will 
obviate the necessity of frequently emptying the cans or treating their 
contents. It may also be stated that where the post holes are quite 
deep and enlarged at the bottom the bugs falling into them will perish 
without further attention. 
OTHER BARRIER METHODS. 
Professor Snow, working in Kansas, followed a somewhat different 
method and one that, under certain conditions, might be found supe- 
rior to that used by Professor Forbes, or the furrow and kerosene 
method applied by myself in Ohio. This modification consists in 
throwing up a double furrow, known among farmers as "back furrow- 
ing," and thus forming a ridge, the top of which is smoothed and 
packed with a drag having a concave bottom of the form of the ridge 
to be made. If the bottom of this drag is covered with zinc it will be 
found to keep bright and polished and by this means make a more 
smooth ridge. The substances used were coal tar as it came from the 
gas works and crude petroleum as taken from the oil wells. The 
former is the more easily obtained, except in certain localities, and 
will probably be found the more practicable, as it stands on the surface 
better and is not so readily washed away by rains. Both of these sub- 
stances are, however, offensive to the bugs, and they will seldom 
attempt to cross them or even come close enough to touch them, but 
on approaching will turn and run along the ridge in the evident hope 
of finding a gap through which they can pass. Post holes were dug 
on the outside of the line, but close up to it, so that the bugs in pass- 
ing along beside the tar line would crowd each other into them. Pro- 
fessor Snow suggests that it will be better to construct this barrier 
several weeks prior to its being needed, as then the tar line has but to 
be run along the ridge and the post holes dug, when the whole system 
is complete and the chinch bugs can be thus shut out from the first.* 
With these barriers of either ridge or furrow and the use of coal tar 
or crude petroleum, supplemented by kerosene emulsion, a very large 
* Fifth annual Report of the Director of the Experimental Station of the Uni- 
versity of Kansas, pp. 45-47. 
