41 
ularly for the destruction of chinch-bugs accumulating on the outer 
rows of corn as they move into the fields from wheat or oats at 
harvest-time. This insecticide method, however, is mainly useful as 
an adjunct to the barrier method already described. 
With a view to testing this operation on a comparatively large 
scale, I instructed Mr. E. P. Taylor, in charge of my field operations 
against the chinch-bug in 1904, to prepare and apply kerosene 
emulsion in the field wherever necessary and practicable in his oper- 
ations, to keep an account of labor required and the cost of materi- 
als, and to observe critically and report the effects of the treatment 
upon both insects and plants. Experiments of this kind were made 
in early July of that year with both kerosene emulsion and whale- 
oil soap. 
In the absence of a mixing pump, the kerosene and soap-suds, 
two parts of the first to one of the second, were thoroughly mixed by 
a simple violent beating with a stick for about five minutes, the ves- 
sels containing the fluids being covered with a cloth to prevent spat- 
tering. Emulsions so prepared, although doubtless not so perfect 
as could be made with a pump, were in every way sufficient for the 
purpose, standing for at least two hours without any appearance of 
a separation of the oil and water, and doing no damage whatever 
to the corn if diluted to contain four per cent, of kerosene. If more 
than this proportion of the oil were used, injury to the plant was 
likely to result, especially if the upper leaves were treated. 
Details of Field Experiments. — AfFairman, July 4, one fifth of 
an acre of corn was sprayed with a kerosene emulsion prepared as 
above and diluted to contain four per cent, of kerosene. No ap- 
paratus was used in making the application, but the fluid was sim- 
ply flirted upon the corn by hand. Ten gallons of the mixture were 
used in this treatment, equivalent to about a barrel (fifty gallons) 
per acre, or approximately one and two thirds ounces per hill. The 
amount of kerosene in a four per cent, mixture used at this rate 
would be two gallons per acre of corn treated. 
Twenty-four hours later none of the plants showed signs of 
injury, and great numbers of the bugs were dead upon the ground 
and in the cups at the bases of the leaves. Living chinch-bugs 
enough remained in this part of the field to extend their attack 
graduallv inwards, until by July 9, five days after treatment, they 
were to be found in small numbers ten rods beyond the area infested 
at first. The number remaining, however, was economically in- 
significant, since no injury to the corn could have resulted. 
A second treatment was applied July 12 to this whole area, now 
about three fourths of an acre in all, twenty-four gallons of the 
