Evening star., 1943-07-11
Milky Disease Reduces Number
Of Japanese Beetles in CAPITAL

The milky disease is cutting down
the number Of japanese beetles in
Washington
Victory gardeners whose plants
have been riddled by the the pests
will find this hard to believe. But
the Park Police. who patrol the
areas where the disease has been in
action, say the damage from beetles
is not nearly as bad as last year.
1t is disease spread by man and
it may become one of the triumphs
of what is called economic ety.
mology; that is, the study of insect
pests in an attempt to save billions
of dollars.
There is hope that Washington
may become immune to the plague
of japanese beetles, because the dis
ease spreads rapidly and continues
in effect for years, killing the grubs
before they develop into a winged
insect
How Name Originated.
The disease is called the milky
disease" because the blood of the
beetle grubs becomes like milk when
they are afflicted 1t was spread in
the parks two summers ago by put
ting a powder made up of the bodies
of diseased grubs and chalk into the
ground at regular intervals. 1t has
now spread enough in the earth of
the parks to be effective.
More than IS tons of this powder
hoQT1 af TTniunySify
of Maryland, in manufacturing
process of amazingly minute detail
in which japanese beetle grubs are
each inoculated with the disease by
hypodermic injection, left in trays
while the disease increases and are
then ground up into the powder.
The. whole State of Maryland has
become an experimental ground in
this new kind of insect control.
Cecil County, north of Baltimore,
which was blacker spot than
Washington on the beetle maps two
years ago, is now relatively free of
the pest.
The japanese beetle was first
found in this country at Riverdale,
N. j., across the Delaware River
from Philadelphia, in 1916. 1t is
thought that grubs of the beetle
came in with some japanese iris
imported into that neighborhood.
Two Men Sent to Japan.
BY 1920 it was so evident that we
had pest of potential destructive
ness on our hands that the Agricul-
ture Department dispatched two
men to Japan to investigate the
parasites of the beetle. The men,
c. B. Clawson and J. L. King, were
in Japan for the next 10 years gath
ering specimens.
When they got to Japan they had
difficulty in finding enough of the
beetles to do their work. 1t was
evident that we were developing
more beetles in New Jersey than
there were in the Japanese Islands.
This scarcity of the beetle in his
own habitat must be due to parasites
which had not followed them to
their new home, so the scientists
watched the life of the beetle in
Japan with increased interest.
They found that little wasp had
a habit of borrowing into the ground
and depositing her egg in the body
of the japanese beetle grub The
wasp grub fed on the beetle grub
and eventually killed it. They sent
back thousands of the waSps.
They cornbed Korea for specimens
of the beetle and its parasites. The
national revolution forced them to
leave China in 1926. They went
into Manchuria.
Wasps Flourish in Scme Areas.
When they returned to the United
States they were succeeded in Japan
by T. r. Gardner, who was succeeded
in turn by L. B. Parker who had
been conducting similar investiga-
tions in India.
The wasps are 1ourishing in cer-
tain sections of New Jersey. Thou
sands of them have been released in
Washington but they have not done
so well here.
The department is basing its plans
for control of the pest on bacteria
found in the soil of the United States
instead of on the parasites imported
from the Orient. This bacteria
causes the milk disease
But we're not kidding ourselves"
one of the Agriculture Department
men said yesterday. 1--WE know that
in time the Japanese beetle will
spread all over the United States.
We are fighting delaying action.
And we hope to trim his numbers
by diseases and parasites so that
he will not be very expensive pest"
In the years that the departments
emmissaries were working in the