Washington standard. [volume] (Olympia, Wash. Territory) 1860-1921, 1913-09-12
HOW TO KILL THE
POTATO TUBER MOTH
Expert Tells Farmers How to
Handle Pest That Costs Cali
fornians Heavy Loss.
ID! VI. 4. Sothrrs. Assistant Entomol-
ogi>t, Washington Agricultural
Experiment StntiOn.)

in California, where it has done hun
dreds of thousands of dollars of dam
age annually. During the last couple
of years this pest has been found es-
tablishing itself at several places with
in our state. 1t has been received in
shipments of potatoes from other
parts of the country. This is the man
ner in which it will get introduced
into new territory, and every precau-
ton should be taken to prevent this
introduction.
The adult moth, which is about one
half an inch from tip to tip of wings
and about one-fourth of an inch in
length and of a grayish color, lays
about 20 peariy white eggs upon the
leaves or upon exposed tubers in early
summer or upon the tubers at digging
time. These eggs hatch into tiny
pinkish white larvae which feed upon
the leaves, stems or tubers, or only
upon the tubers when they are stored
in bins during the winter. They bur
row all through the tubers, rendering
them useless and unfit for food.
In from four to six weeks the larvae
get their growth, and then they seek
sheltered place, spin cocoons about
themselves and transform into pupae.
In the summer this pupal stage lasts
about two three weeks and the adult
moth appears again and lays eggs for
second brood of larvae. The moths
live but few days. By late fall the
larvae have developed into the pupal
stage, in which state they remain over
winter adult moths appearing in the
spring. The adult moths are night
f1iers, and if tubers are left exposed
over night when dug in the fall, the
moths take occasion to lay their eggs
on them, thus causing an infestation
in the tubers in storage.
The potato tuber moth is difficult to
control, as it is impossible to reach the
larvae in the mines in the stems and
tubers in the field. This makes it nee
essary to proceed against the pest by
other methods, of which several should
be employed for the best results.
First: Only those potatoes known
to be absolutely free from any signs
of the pest should be used for seed.
Second: Deep planting and killing
should be practiced.
Third: With this, as with most all
other insect pests, one of the most i'm
portant measures of control is clean
culture. All weeds in and about the
potato patches should be destroyed by
burning. This will eliminate breed
ing and alternating places for the in
sect.
Fourth: Potatoes should be dug as
early in the fall as possible, and not
allowed to remain in the field over
night unless carefully covered.
Fifth: At digging time all tubers
found infested should be put in bin
and fumigated. Infestation can be de-
tected by the presence on the tubers
of the excrement of the moth. After
the tubers have been sorted and placed
in the bin they should be fumigated
with carbon bisulphid Cor bisulphid
of carbon, as it is also known) in or
der to kill any stage of the insect |
present at this time.
Carbon bisulphid is applied by pour
ing it into fiat vessels, such as pie |
tins or milk pans. An average of
three pounds should be used in each
one thousand 10000 cubic feet of air
space. The gas, being heavier than
air, penetrates downward through the |
mass to the bottom. The bin should
be tightly closed for "a to SO hours, |
without injuring terminating power
of the potatoes.
AS this gas Is very infiammable, and
serious fire or explosion may result, !
the utmost care should be taken that
no fire. such as lighted cigar, cleo
trio fan, stove, or gas light or lamp
should be brought into the vicinity of
the gas. The gas is also very poison
Gus and should not be breathed. Upon
opening the fumigating bins they
should be aired for at least "a hours in |
order to remove all danger from fire
or explosion, and also to remove the
offensive odor.
Sixth: Sheep and hogs are valua |
bic for the destruction of such rem
nants as are likely to be left lying
about in the field at digging time and
should be turned into the field when
the potatoes are removed
Seventh: Crop rotation is valuable
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