The Dickinson press., 1916-01-01
NEW INsEcTIcIDE.
Arssnats Of Calcium Effective Aaainst
Chewing Insects on Fruit Trees.

Arssnats Of Calcium Effective Against
Chewing Insects on Fruit Trees.
Prepared by United States department OF
agriculture.l-
AS a result of extensive tests with
different insecticides the entomologists
of the department have found that
calcium arsenate, new insecticide,
gives very promising results in the
control Of certain insects that do dam.
age by chewing on fruit trees. Among
the chewing insects against which the
arsenate Of calcium proved effective
In laboratory and field tests conducted
at Benton Harbor. Mich. are the cod
ling moth, the fall webworm, the tent
caterpillar and the tussock moth.
In these tests the effects of arsenate
Of calcium, both alone and combined
with lime-sulphur solution. were test
ed In comparison with arsenate of
lead alone and in combination with
1me-sulphur. The arsenate of calcium,
as was the arsenate Of lead, was used
at the rate Of two pounds to each fifty
gallons Of water. In all the expert
ments the arsenate Of calcium gave
very satisfactory results in killing the
larvae without burning the foliage. In
number Of cases it's killing action
was somewhat slower than, but COM
pared favorably with, the arsenate of
lead. Since it can be produced more
cheaply than the lead arsenate it would
appear to have distinct value, although
1t has not been sufficiently tested to
permit recommending it unreservedly
for general use. Where arsenate of
calcium was combined with lime-sul-
phur 1t was. as rule, even more ef-
fective as a poisoning agent than when
used alone and did not lessen the value
OF the latter as a fungicide. When
these compounds are combined the
amount of foliage consumed by the
larvae Is less than where the arsenate
Of calcium is used alone. In tests in
1914 a commercial arsenate Of calcium
paste). arsenic oxide 1882 per cent,
with lime-sulphur solution gave very
excellent control Of the codling moth
in comparison with arsenate Of lead
and with unsprayed plats. Where
arsenate of calcium was used 1919
per cent Of the apples were sound;
arsenate Of lead showed 99.44 per cent
of sound apples, while in the unspray-
ed test plats only 5S.71 per cent of the
apples were free from damage.
Tho fo110Nyiro will l,o Qo,,r5 ~ -
convenient way Of making homemade
arsenate Of calcium:
Stone lime 600 per cent CaO). lbs, SIS
Sodium arsenate. fused (dry powdered),
10 per cent -AssOs lbs, 100
Place the stone lime in a wooden con-
tainer and add a small amount Of wa
ter, just enough to start Stacking
When Stacking il; well under way pour
in the sodium arsenate. which should
first have been dissolved in hot water
Keep stirring, until the lime has thor
oughly slakel Sufficient water should
be added from time to time to prevent
burning F"
The, resulting arsenate Of calcium
should contain about IS per cent of ar
senic oxide. In making this compound
1t will, Of course. he necessary to know
approximately the calcium oxide and
arsenic oxide content of the materials
employed and to vary the formula ac-
cordingly. The byproduct is largely So
dunn hydroxide, which should be de-
canted If the insecticide is to be used
on tender foliage.