Lady Bugs
From numerous western Washington accounts, lady beetle populations have been
increasing bringing to mind the following questions: What are they? Why are
there so many? How can I get rid of them?
The species found so abundantly is the multicolored Asian lady beetle,
Harmonia axyridis, common in Japan, Korea and other parts of Asia.
"Multicolored" refers to the tremendous color variations in this species,
ranging from black with two red spots, to red with 19 black spots, with every
combination in between. This species was introduced by USDA Agricultural
Research scientists in the late 1970's and early 1980's as a biological control
agent for pear psylla and other soft bodied insects.
Numerous releases occurred in the United States; high populations have been
reported in Washington, Oregon, Georgia and Virginia. Releases in Washington
State were in Chelan, Klickitat and Yakima Counties, all east of the Cascade
Mountains. The insects apparently did not establish in eastern Washington, but
chose to relocate in western Washington. Others may have arrived here as
unintentional passengers aboard cargo ships from the Orient.
Introduced insects often require 7 to 10 years to become established, thus
the reason we are only now witnessing observable numbers. Being a recent import
few natural enemies are available to keep Harmonia axyridis populations
in check. This will necessitate management efforts by homeowners until the
beetle population experiences a natural reduction.
Most lady beetle adults spend the winter months in clusters, protected from
the weather. In their native home, Harmonia axyridis overwinters in
cliffs, but in Washington, unfortunately, the next best thing is a house.
Attracted to vertical surfaces, they often appear on light-colored walls with a
south or southwest exposure. These 1/4" long insects enter wall voids through
cracks and settle down for the winter. With lengthening daylight, a warm
interior often draws them inside which can be frustrating to human residents.
Lady beetles are beneficial insects and should be preserved, if possible.
Locating entry points and sealing up cracks and crevices will help reduce their
numbers indoors. Window screens and doors should be tight-fitting. Concentrate
initial efforts on the south and west sides of infested structures. Each day,
vacuum and dispose the beetles well away from the building, as these insects are
strong fliers and will readily return. A wet-dry vacuum works quite will for
this. If entry points are still available, there may seem to be little reduction
as new beetles enter. Vacuuming the clusters from walls during fall may also
offer some relief.
We have have that by combining two products, (permethrin
& Nylar IGR) we have had the most success in
controlling Lady Bugs. For even a faster knockdown, you can add some
EXCITER Pyrethrin Concentrate.
One other tip; if you had a little liquid detergent to your solution it tends to
stick to vertical surfaces a little longer.
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