Evening star., 1941-07-05
Control for
Japanese
Beetles
Artificial Spread
Of Pest Disease
Being Studied

Artificial spread of the milky dis
ease of Japanese-beetle grubs is be-
ing continued this year in a number
of Eastern States. according to the
U. S. Department of Agriculture.
The milky disease is harmless to
human beings, animals and plants.
but in the spore stage is fatal to a
high percentage of Japanese-beetle
grubs. This disease has been re-
sponsible to q considerable extent
for decrease in Japanese beetles in
older infested areas.
The department, in cooperation
with State agencies, is speeding up
the natural spread Of the disease
by introducing it at various points
in beetle infested areas. Except for
certain government-owned proper
ties in Washington and elsewhere,
department distribution of the dis
ease is not complete.
More intensive distribution has
been undertaken by several cooper
ating States, including Maryland,
Connecticut, New York and New
Jersey. Ali distribution is through
ofiicial agencies. The disease organ
isms are not available to private
individuals or organizations.
The milky disease of the japanese
beetle is the most effective natural
control agency yet discovered. The
disease organisms are remarkably
resistant to dryness or moisture and
to high or low temperatures They
apparently remain alive in the soil
for long periods, ready to infect and
kill successive broods of Japanese
beetle grubs that make their way
through the soil to feed on plant
roots. Even milky disease bacteria
that pass through the digestive
tracts of birds and small animals
that have eaten grubs, remain alive
and are reintroduced into the soil.
The milky disease bacteria do not
develop to the spore stage in arti-
fetal culture media. The Bureau of
Entomology and Plant Quarantine
has developed practical method
of culturing the organisms and has
invented a micro-injector for in
oculating healthy Japanese-beetle
grubs with measured doses. Grubs
that die of the disease are ground
and mixed with tale, the mixture
being placed in spots or busted over
the ground. Grubs affected with
the milky disease become milky
white in appearance. The dead
grubs disintegrate but the disease
bacteria remain alive, to affect later
broods Of beetles.
Introduction of milky disease of
the Japanese beetle is expected to
help considerably in reducing ex-
treme infestations and may prevent
beetles in new locations from be-
coming as numerous as in older in
festations. 1t cannot be counted on,
however, to eliminate the Japanese
beetle entirely, or to prevent spread
to new localities. Plant quaran-
tines by the Department Of Agricul-
ture retard long-distance spread OF
the insects on shipments on farm
or nursery products.
Each summer thousands of traps
placed by the department outside
the quarantined areas serve as
scouts" to find out whether the
beetles have reached new territory.
Traps painted primary yellow are
much more attractive to the beetles
than the green-and-white traps
formerly used, tests have shown.
The trap bait the beetles like best
is a mixture of 10 parts of geraniol
and one part of eugenol. Japanese
beetle traps are on the market, but
are not available from the Depart
ment Of Agriculture.
In the latitude Of Washington,
D. c., and Philadelphia, the first
Japanese beetles usually come out
of the soil sometime between June
10 and 20, according to the Bureau
Of Entomology and Plant Quaran-
tine. Farther north, they appear
later; farther south, earlier. On
warm, sunny days, they fly about
and feed on plant life, but in cool
or cloudy weather do little feeding.