Asian lady beetles (Iowa State University Extension)
Now that Halloween is past, it鈥檚 a piece of cake to clear the decks of the ersatz bats, spiders, and other things that go bump in the night and plague the kiddies鈥 dreams. But one terror remains on the scene all winter.
Multicolored Asian lady beetles, or Halloween ladybugs as they鈥檙e often called, tend to invade houses at this time of the year. They鈥檙e only looking for a nice place to stay warm for the winter. When they find it, they sometimes release 鈥渁ggregating pheromones,鈥 or odors that attract their kin. Lots of them. The large clusters of this species seen around windows or the corners of rooms tend to spook out housewives and mister moms.
A few people say these beetles bite, and if you squash one, its yellowish blood is stinky. They may be a nuisance, but not really a physical threat. And next summer they鈥檒l perform Herculean tasks, eating zillions of aphids and other pests in home gardens. But for now, for some homeowners, ghosts and ghouls are preferable to these pretty little insects.
How did the beetles get here from Asia? Good question. The U.S. Department of Agriculture released them in a number of states to control pest insects, beginning around World War I and continuing up through the early 1980s. But now USDA seems to disown those earlier generations. There exists no evidence the importations succeeded, so maybe there were no survivors. But then a large infestation occurred in Louisiana in the late 1980s, an event that USDA suggests came about when the beetles escaped from a visiting freighter. What freighter? So no one really knows if today鈥檚 surging throng originated from a regrettable accident or a purposeful introduction. Maybe both?
Whatever the cause, Halloween ladybugs are almost omnipresent east of the Mississippi and on the West Coast, probably to stay. The controversy over their behavior stands as an example of the Mother Goose Syndrome: 鈥淎re they good animals or bad animals?鈥 I like to see them as simply another interesting addition to our American wildlife.