40 
At Odin was a small field of infested wheat, containing four 
acres, with corn bordering it to the north and west. A tar and post- 
hole line was carried along these two sides for about a thousand 
feet to prevent the passage of the bugs across the boundaries. 
The conditions and results at both these places were so similar 
to those at Fairman that no detailed account is necessary. At Odin 
a simple method was made use of for preparing the ground for the 
tar. A heavy plank was dragged endwise back and forth about ten 
times along the edge of the wheat, thus smoothing and packing well 
a strip two feet wide. With a short-handled shovel the ground was 
then packed and pounded to a hard surface, in which a narrow and 
shallow groove was made with the shovel handle for the reception 
of the tar. This was poured in a stream the size of a lead-pencil 
from the spout of a watering-pot from which the sprinkler had been 
removed. The line so laid spread out on the ground to a width of a 
half to three quarters of an inch. 
Experiments with Fluid Insecticides. 
In my first report, the twelfth of this office, published in 1883, 
is a description of the first attempts made to destroy chinch-bugs 
by means of kerosene mixtures. In the operation there reported, 
nineteen experiments were made, mainly with emulsions varying in 
strength from two and a half to six and two thirds per cent, of kero- 
sene, but partly with mechanical mixtures of the crudest kind. 
These insecticide fluids were sprinkled upon infested hills of corn 
during the last days of July, partly transplanted hills which had been 
removed to my office laboratory and partly hills in the field isolated 
by surrounding them with barriers of boards and coal-tar impassable 
to insects on foot. Proper checks were kept in all cases of hills 
treated precisely like those under experiment except that plain water 
was substituted for the fluid insecticides, A single additional experi- 
ment was made with strong soap-suds to which no kerosene had 
been added. 
The general result of a single application of any of these mix- 
tures was the destruction of about eighty per cent, of the bugs on 
the corn at the time, the remaining twenty per cent, being either 
protected by their position from contact with the insecticides or re- 
viving after a time without noticeable injury. Most of the escaping 
specimens were apparently on the ground under clods of earth 
when the corn was treated. 
Frequent use has since been made of the kerosene mixtures in 
field experiments by ourselves and by other entomologists, partic- 
