Question: I know lady bugs are supposed to be good, but
in our house in Maine this fall we had hundreds of them in the
house and on the side of the house. Why in the Fall?
following information was adapted from an article by Dan Suomi,
an entomologist with the Washington State Department of Agriculture
(Down the Garden Path Newsletter, April 14, 1994 #60).
The species found so abundantly is the multicolored Asian lady
beetle, Harmonia axyridis, common in Japan, Korea and
other parts of Asia. The name "multicolored" refers
to tremendous color variation in this species, ranging from black
with two red spots, to red with 19 black spots, and about every
combination in between. They were 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
In their native home, Harmonia axyridis overwinters
in cliffs, but in the United States, unfortunately, the next
best thing is a house. Attracted to vertical surfaces, they
often appear on light-colored walls with a south-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. Residents become frustrated
because daily vacuuming does not seem to rid the structure of
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 inside homes. Make certain
that screens and doors are tight-fitting. Concentrate initial
efforts on the south and west sides of infested structures. Each
day, dispose of vacuumed up beetles well away from the building,
as these insects are strong fliers and will readily return. A
wet-dry vacuum works quite well for this. Vacuuming the clusters
from walls during fall may also offer some relief.
For more information refer to publication E-214
Asian Lady Beetles (PDF 32K). (NOTE: This
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