39 
ordinary farm scraper, making a strip about two feet wide, one or 
two inches below the general level. It was necessary, however, to 
scrape the surface afterwards with a shovel or hoe, as many irreg- 
ularities were otherwise left to carry the tar in all directions. The 
labor of a man and team for half a day would be rec|uired to pre- 
pare eighty rods in this way. 
Finally, the sixth section, eighteen rods long, was made in 
meadow land by plowing two shallow furrows, throwing the dirt 
outward in a way to leave a level dead furrow about two feet wide, 
and smoothing and leveling the bottom more exactly by hand. 
This is a rapid and satisfactory method of preparation where a 
barrier can be made in sod with room to work a team. 
The tar line was made by pouring from a watering can a slender 
stream of tar continuously along the ground. Holes were then dug 
with an ordinary post-hole digger to a depth of about a foot and at 
a distance of twenty feet apart. They were placed on the stubble 
side of the line, and short diagonal lines of tar were laid from each 
hole to the right and left in a way to conduct chinch-bugs approach- 
ing the line to the hole itself. Six gallons of tar were needed to 
construct this barrier along the eighty-rod boundary. During the 
period of twelve days covered by this experiment, the tar line was 
renewed eighteen times in all, as many as three times a day at first, . 
while every other day was sufficient towards the end of the period. 
Fifty-five gallons of tar were used in these eighteen operations, 
an average of three gallons for each time. The cost of the tar for 
this period was $2.40, or twenty cents a day for the twelve days. 
This line was of course effective from the first, and bugs were 
continuously caught in the holes along it, where they were easily 
killed with tar-water or kerosene. 
Diihois and Odin Bxperiments. — At Dubois, in Washington 
county, an irregular field of corn containing twenty-eight acres was 
protected from invasion by chinch-bugs from two fields of wheat 
adjoining it. On the east side along a boundary line of two hun- 
dred and fifty yards a double barrier was constructed, a furrow next 
the corn and a tar line with post-holes immediately outside. To the 
west and north a tar line was laid seven hundred and sixteen rods 
in length, and post-holes were dug every twenty feet. Although 
the chinch-bugs proved not to be sufficiently numerous in the wheat 
to have caused any great injury even if they had escaped into the 
corn without hindrance, these barriers were as carefully maintained 
for eleven days, from June 29 to July 10, as if the salvation of the 
corn depended upon their efficiency. 
