Friday, November 5, 2010

Asian Lady Beetles

Last week, shortly after the first freeze of the year, I was up at Three Trees, an open vista on a ridge with three large oaks in a cluster.  Each time I stopped there I noticed little bites on my exposed skin.  I was being swarmed with Asian Lady Bugs, Harmonia axyridis, which I hadn't encountered anywhere else.  Each afternoon this would occur only there.  Swiping them off my skin left their faint foul scent on my hands.

Why only here?  Tim Smith answered the question in the Missouri Conservationist Ask the Ombudsman column several days later.  To quote him:
"Each fall, during a warm-up following the first cold weather, the insects gather on the sunny sides of houses and other structures as they look for cracks and crevices where they can find shelter from the coming winter.  Many will survive the winter and appear again in the spring as temperatures warm and they try to exit the house."
Hackberry Bark
 Right beside the three shaded oaks stands a large hackberry tree, its bark exposed to the warm sun.  And there they were, crawling around its deep bark fissures, looking for a warm winter shelter.  At least these were out in nature rather than joining the hundreds that choose to live with us at our house.

Tim provided more information on the MDC Fresh Afield blog last year.  According to Wikipedia, they were brought to the United States in 1916 to control insect pests of plants, but were not successful.  In 1988 they were observed in numbers in New Orleans, and since then they have spread.  By 1995 they were occasionally found in the Midwest and became common in 2000.

Subsequently, they have also contributed to the decline in native ladybugs, presumably by out competing them.  They also have reached pest status to the higher biped mammals, both because of the swarming numbers, their little bites and unpleasant odors and the tendency to move into our buildings.  For information on these pests including control recommendations, check out http://ohioline.osu.edu/hse-fact/1030.html

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