32 
twenty feet apart along all these lines ; and besides the continuous 
coal-tar strip, diagonal leaders about a foot in length were laid from 
each hole outwards in two directions, as shown in the accompany- 
ing diagram (Fig. 2, p. 131)- 
Summary of Conclusions. 
As a general outcome of the work at these various places, it 
was demonstrated that an effective barrier against the movement 
of chinch-bugs may be maintained for four weeks with coal-tar, 
poured along a strip of ground properly prepared, at a cost for 
materials of seven cents a rod, or $22.40 a mile, and that virtually 
all the bugs approaching these lines may be trapped and killed in 
post-holes properly placed for the purpose. 
The time for which this barrier must be kept intact will vary 
from ten days, the period found necessary in the very dry weather 
of 1896, to thirty days, as required this year. The labor necessi- 
tated is that of raising a ridge by plowing a back furrow between 
the infested field and the one to be protected, smoothing and packing 
this strip with a light roller or by hand, digging a row of post-holes 
at intervals of about twenty feet, and laying the lines of tar by pour- 
ing it upon the ground from a can with a tubular spout. This line 
was renewed whenever it became dry or hard in the sun, or when it 
was covered with dust in windy weather or washed away or cov- 
ered with mud by rains. It was necessary to pour fresh tar along 
the line from one to three times a day, the average at all places for 
the month being three renewals every two days. 
Use of Kerosene Emulsion. 
Where chinch-bugs had entered corn before the experiment was 
begun, and where, through accident or mismanagement, they es- 
caped across the barrier, they were effectively treated with a four 
per cent, kerosene emulsion. It was shown that a mixture suffi- 
ciently complete and lasting for the purpose could easily be made 
by stirring the kerosene and the soap solution together with a stick 
or paddle, and that this emulsion could be conveniently applied by 
sprinkling or throwing it on the infested plants with a whisk-broom, 
or even with the bare hand. Thus prepared and used, the four 
per cent, emulsion was as strong as the corn would stand without 
some injury, and was sufficient to kill all the chinch-bugs which it 
touched. 
The only notable failure of this method to destroy the chinch- 
bugs against which it was used, occurred where the infestation of 
