™ Aone ate vary 
46 Contagious Diseases of the Chinch-bug. 
cient and are more generally available than the coal-tar. The 
coal-tar can be easily applied by means of an old teakettle, 
sprinkler, or coffee-pot. The stream poured upon the ridge 
need not be more than half an inch in diameter, and when of 
this size the operator should walk rather rapidly in applying it. 
Where coal-tar is not available, crude petroleum or kerosene 
oil may be mixed with common coarse salt and a line of this 
may be strewn on the ridge with the hand or in any other man- 
ner preferred by the operator. All of these substances are © 
cheap enough to be profitably used. 
The results of this method of combating chinch-bugs were well 
shown by experiments in a wheat-field. The bugs were noticed 
early in this wheat, and just before harvest and before the bugs 
had migrated to the corn the ridge was thrown up, coal-tar was 
applied and the post-holes dug. The bugs which collected and 
died in the first few holes were taken out and piled near the 
holes in great quantities. Only a few bugs escaped, and no 
damage was done the corn. 
In another case, the bugs had left the wheat and Hal ad- 
vanced about 50 rows in the corn, destroying it utterly as they 
advanced. Sporotrichum had been: scattered abundantly in the 
field, but although many bugs died of the disease, the injury 
to the corn was not materially abated. Then the ridge was 
thrown up,, tar was put on, and post-holes dug. The result > 
was that the bugs were caught and died in the holes, so that 
the corn suffered no further injury. These two instances dem- 
onstrate the value of the barrier method described above. 
Equally good results were obtained with kerosene oil mixed 
with salt. If the ridge is not formed and the offensive sub- 
stances are simply spread upon the ground, the bugs, when in 
great numbers, crowd each other across the barrier, those in 
front being unwillingly carried forward by those behind; or, if 
the post-holes are omitted, the bugs are not destroyed, and 
manage finally to straggle into the corn-field after the barrier 
has become damaged by the weather. ° 
The barrier method has the advantage of not being dependent 
upon a complexity of conditions for its success, and of giving 
immediate results. It has the disadvantage of being only ap- 
plicable at the very short time when the bugs are migrating 
from one field to another. It cannot be used upon bugs already 
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