Fort Dodge Messenger, IA
10-06-07
Asian lady beetles migrate into area
Bugs accidently introduced in U.S.
By KRISS NELSON, Messenger correspondent
Not only is fall related to the beautiful color of changing leaves, but is also
associated with a colored nuisance: the Multicolored Asian Lady Beetle.
Donald Lewis, Iowa State University Extension entomologist said now is the
time when we will begin to notice the multicolored Asian lady beetle with midOctober historically being the highest migration period.
The MALB has become quite familiar throughout the United States and Iowa and
contrary to popular belief that they were introduced into the country as a means
of controlling aphids; they were brought here by accident.
“They were not brought to Iowa,” said Lewis. “They got here on their own. An
invasive variety was accidentally introduced at a port in New Orleans in 1988.”
The MALB is 1/3 inch in length; dome-shaped; yellowish-orange to red with
variable black spots on the back. Deep orange is the most common color. These
beetles are outdoor insects that create a nuisance by wandering indoors during a
limited portion of their life cycle and wooden residential and industrial areas are
especially prone to problems.
MALB do not feed or reproduce indoors and cannot attack the house structure,
furniture or fabrics. Fortunately they do not sting or carry diseases nor feed on
people, but they infrequently pinch exposed skin. They follow their instinctive
behavior and fly to sunny, exposed surfaces when preparing to hibernate through
the winter, making light colored buildings and walls in full sun appear to attract
the most beetles.
The populations of MALB, Lewis said vary greatly from year to year and place to
place.
“There are sometimes enormous numbers over a wide area of the state and
other places there’s very few. The population depends where you are and the
weather in the summer,” said Lewis.
This year potentially could see lower populations migrating into homes and Lewis
believes this may have to do with the warm March then early freezes, however
due to the dry weather the MALB’s had plenty of food over the summer due to
the high aphid populations.
“The food supply and weather cause numbers to be up or down or both,” said
Lewis.
Once they make it into your home, Lewis said the MALB often don’t live long
because of dehydration, as they flourish in cold, damp areas.
Now is the time, Lewis said to begin bug-proofing your home by sealing exterior
gaps and cracks around windows, doors, eaves, roofs, siding and other points of
access before the beetles appear.
“Seal all the cracks and gaps as well as you can — eaves, windows, doors,
screens, gaps at the foundation and siding — it will help.”
For large infestations with intolerable numbers of beetles, spraying pyrethroid
insecticides such as permethrin or esfenvalerate to the outside of buildings when
the beetles appear may help prevent pest entry, but not necessarily the best
choice of control, Lewis said due to the large amounts of insecticide that has to
be used and having to reapply and if the numbers of beetles are super abundant,
it may not make much of a difference.
If the MALBs do make their way into your house, Lewis said you can spray
exposed bugs inside as well, but again could mean a lot of insecticide inside your
home and most indoor sprays are of very limited benefit.
The most practical way to help control MALB, Lewis suggests is vacuuming or
sweeping them up and discarding them.