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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
far indicate that this form of cyanide is well adapted for soil fumigation. Hydro¬ 
cyanic acid gas is readily given off and the powder is easily applied in the soil. It 
would be possible to apply it in the soil on a large scale by means of a drill. Woolly 
aphis and other soil infesting insects have been killed with the use of 2 oz. per sq. yd. 
Little has been determined thus far as to the effect of the powder on the roots of 
trees but the indications are that it is less injurious than a solution of any form of 
cyanide. 
A few preliminary experiments have also been made with the peach root-borer. 
Where the material was applied directly to the tree a good kill of the borers resulted, 
but the effects on the tree remain to be determined. It is also planned to make tests 
against nematodes where these occur with normal crops. It has already been used 
with considerable success against ground squirrels. The University of California 
Citrus Experiment Station is engaged in an investigation of the uses of powdered 
calcium cyanide as an insecticide and, at the present time, the work has proceeded 
far enough to indicate merely some of the possibilities rather than to make any 
definite claims supported by sufficient data. 
H. J. Quayle, Citrus Experiment Station, Riverside, Calif. 
Calcium Cyanide for Chinch Bug Control. Experiments with Calcium Cyanide 
for control of the chinch bug were started at Illinois, in June 1922. The material 
was used at first in flake form, as this was the only form procurable, at that time. 
It was scattered along the margins of stubble fields, from which chinch bugs were 
migrating to the corn, and used along barriers where the bugs were stopped in their 
migration from the small grain fields. When scattered over the ground, in a strip, 
three inches wide, and sufficiently thick, so the flakes were not more than an eighth 
of an inch apart, it was found that this material would kill every bug crossing it, for 
one hour to three hours, depending on the temperature, the amount of moisture in 
the soil and the humidity. The flake material was scattered around the base of 
hills of corn, and behind the sheathes of lower corn leaves, heavily infested with 
chinch bugs. Practically 100% of the bugs on the corn hills treated in this way, 
were killed, where they were feeding within three inches of the Cyanide flakes. 
During the latter part of the summer, a dust cyanide was secured, and was tried 
at strengths of 3 r 6, 9 and 12% in a ground spent tobacco dust carrrier. The 3 and 
6% strengths, gave only a fair degree of kill, when dusted on chinch bugs in grass or 
behind leaves of corn stalks. The 9 and 12% strengths gave a much better kill, 
the 12% killing about 95 to 98% of the bugs, within three inches of the point of 
application. 
During the past winter, this material has been tested, on hibernating chinch bugs, 
placed in wheat and on the bare earth in a greenhouse. The results obtained from 
these experiments have confirmed the work of the previous summer. Extensive field 
experiments, to test the effect of this material combined with different carriers, and at 
different strengths, will be carried out in Illinois and neighboring states, during the 
coming season. If the material proves as effective as indicated by the experiments 
of last year, it will be possible to use it for field applications, against the chinch bug. 
The cost of such application would not be so high, that it would be impractical for 
a farmer to use it. 
W. P. Flint, State Entomologist, Natural History Survey, Urbana, Illinois 
