For most of the year they are a welcome army that defends leafy crops from Kittery to Eastport.

But every October, ladybugs march into homes and businesses, clinging to walls and ceilings, hoping to find somewhere warm to spend the winter.

The ladybugs, or more precisely, multicolor Asian lady beetles, are making their pilgrimage indoors at this time of year, and to homeowners in southern Maine, they are sometimes unwelcome when they cluster around windows and doors seeking warm spots.

There are nearly 60 varieties of lady beetle in Maine, with the multicolored Asian lady beetle among the most common.

“They have a strong tendency to come inside,” said Clay Kirby, an entomologist at the University of Maine’s pest management office.

Kirby’s office fields all manner of bug-related questions. Every year, he said, he gets calls about indoor infestations of the beetles.

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“Too much of a good thing can be a problem sometimes,” he said.

Kirby said the ladybugs are benign, and are helpful in controlling other insects that are harmful to plants, such as aphids.

They have often been deliberately released for the purpose of insect control, starting as long ago as 1916.

Where they do pose a problem for homeowners, however, is when large numbers of them come indoors.

Although they don’t breed, lay eggs or feed inside, they can stain surfaces. Squashing the little beasts can also produce a slightly foul, bitter smell.

Kirby said ladybugs can be removed by sweeping them from walls and ceilings and tossing them outside, or by vacuuming them from whatever surface they’re clinging to.

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For those who don’t want to kill a helpful insect, he said people can round up the bugs and store them in a shoebox in a garage or shed until spring.

Scientists theorize that the creatures first showed up in the United States in the Mississippi Delta area after arriving from Asia in the early 1900s, either accidentally or for pest control.

From there, they spread north through the Mississippi River valley and then eventually migrated east into New England and other parts of the nation.

The migration did not land in Maine until the 1990s, Kirby said, when their arrival had at least one unexpected positive effect.

“In our experimental corn plots, we used to have a pretty significant problem with corn leaf aphids,” he said. “When these things showed up in the state of Maine, they just wiped out the corn aphids.”

Ramona Snell of Snell Family Farm in Buxton said ladybugs are not unwelcome visitors for her, even if they do occasionally manage to get into the farmhouse.

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“We’ve noticed a lot of them flying around, but we’re kind of happy they’re here. They don’t bother us,” she said, noting that they help keep aphids in check.

Over in Dayton, Rachel Harris of Harris Farm agrees they’re more of a benefit than a pest, even when they crowd onto windows or the outside of the house.

“I don’t even vacuum them up in my house,” she said. “I just let them do their thing.”

Staff Writer Gillian Graham contributed to this report.


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