REMEDIAL MEASURES AND CONCLUSIONS. 51 
rains tend to wash the oil off, but it can be renewed easily with a 
garden sprinkler. Under ordinary conditions the original oiling will 
probably suffice. 
The volatile products of the oil keep the bugs from crawling be- 
neath the barrier, and the difficulty of crawling along straws lying 
in every direction and coated with the offensive-smelling oil discour- 
ages the bugs from their attempts to crawl over. 
It is to be regretted that the oiled-straw barrier was not thought 
of soon enough to make a test of its practicability in protecting an 
entire field. A small patch of corn in a field into which the invasion 
of the bugs had already begun was surrounded by a barrier of this 
kind in order to ascertain its effectiveness. A few bugs were already 
in the corn inclosed by the barrier, but these were removed by hand 
and thrown outside. Any bugs that were subsequently found in the 
corn, therefore, presumably had crossed the barrier. The experi- 
mental corn patch lay in the direct line of march of the principal 
mass of migrating bugs. 
The barrier was prepared June 23, 1910. During the next five days 
no fresh oil was applied, and a torrential rain washed out some of the 
oil with which the straw was originally saturated, leaving the upper 
straw odorless and reducing the oil beneath, so that the odor was 
faint. As a result, a few chinch bugs were found crossing the bar- 
rier on the uppermost straws. None was passing underneath. A 
second application of oil was made with a garden sprinkler. Had 
it been made immediately after the rain, probably no bugs would 
have crossed the barrier. No further application of oil was made. 
The field was inspected July 6. Only a trace of rain had fallen in 
the meantime, and the barrier had retained the odor of the oil, and 
consequently retained its effectiveness throughout the remaining pe- 
riod of the attack. 
The bugs within the inclosure were so few in number that no ma- 
terial damage was done to the corn, and consequently the stalks had 
made a nearly normal growth and presented a striking contrast to 
the corn outside of the inclosure, which lay withered on the ground. 
No postholes had been dug, so that the insects encountered the bar- 
rier, passed around it, and then straight on into the corn beyond. A 
few, however, turned into the corn back of, and protected in part by, 
the inclosed patch. But as they did not damage it much, it grew 
and appeared nearly as vigorous as the corn within the barrier. By 
July 28 the chinch bugs had scattered, but they had left a trail of 
destruction in their path, all the corn being killed except the small 
patch protected by the oil-straw barrier and the corn immediately 
back of it and an occasional stalk here and there which had escaped 
serious injury. (See PI. V, fig. 1.) 
A harrier inclosing a field versus a harrier along one side only. — 
Barriers are usually erected only between the field from which the 
