Ill 



eleven days, of which $13.33 was the value of the labor and $10.08 the 

 cost of the tar used. This was at the rate of $2.13 per mile for each day 

 of the time during which the barrier was kept up, of which $1.21 per 

 mile per day was the value of the labor and ninety-two cents the cost 

 of the tar used. 



An attempt was made to measure the bugs caught in the post- 

 holes, and 3y 2 bushels were actually collected ; but heavy rains on July 

 2, 3. and 4 filled the holes with mud and water, and made further 

 measurement impracticable. On the sides of the field where the post- 

 hole traps were a hundred feet apart, many of the bugs attempting 

 to escape failed to find them and were either killed by the hot dust of 

 the barrier ridge or entangled in the coal-tar line and thus escaped 

 our measurement. If we take the 3y 2 bushels as the total yield of the 

 operation, the cost was $5.02 per bushel of chinch-bugs, of which $2.16 

 was for coal-tar and $2.86 for labor. As there are about 8,500,000 

 chinch-bugs to the bushel at this time of the year, this was at the rate 

 of nearly 17,000 dead chinch-bugs for each cent of the expense. When 

 we take into account the fact that these were all bugs of the first gen- 

 eration of the year, and that if allowed to escape they would presently 

 have bred a second generation to infest the corn at a rate, according 

 to previous observations and estimates, of about 100 to 1, it is easily 

 seen that this was an immensely profitable operation to the community 

 as a whole and immediately useful also to the farmer concerned, as 

 saving his corn from destruction where it lay beside wheat. 



In a field near Patoka, in Marion county, a barrier seventy rods in 

 length was maintained for twenty-seven days, June 28 to July 24, 

 between a field of infested wheat and one of corn immediately adjoin- 

 ing. The difference in time during which the barrier was maintained 

 in this field and in that at Oakdale was due to the quick destruction of 

 the wheat in the Oakdale field by insect infestation which compelled 

 a prompt escape of the bugs to obtain food. In this Patoka field it was 

 necessary to renew the tar-line thirty-seven times and to use sixty-five 

 gallons of coal-tar in so doing. The labor in this case amounted to 

 $4.80 and the cost of the tar was $4.04. — a total expense per mile of 

 barrier of $40.42, of which the labor item would be $21.95 and that for 

 coal-tar, $18.47. This is equivalent to $1.49 per mile for each day 

 during which the barrier was maintained; but of this sum only sixty- 

 eight cents per day was for the cost of materials. 



The third demonstration field of this season was near Dubois, in 

 Washington county, where a tar line a hundred and twenty-eight rods 

 in length was maintained for nineteen days, June 21 to July 9. In 

 this case tar was poured upon the barrier ridge thirty-eight times — an 

 average of twice a day — at a cost of $15.77, of which $6.80 was for labor 

 and $8.97 for tar. The latter sum was regarded by the field superin- 

 tendent as excessive, the tar having been wasted by too liberal use in 

 pouring. This was a total expense for the season of $39.43 per mile 



