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The ladybugs that plague Pennsylvania homeowners during the fall and winter months soon will be migrating from trees and fields into houses.

"Originally introduced in the southeastern states as a biological control agent, the multicolored Asian lady beetle has spread from orchard settings to fields and forests," said Dennis Wolff, secretary of the state Department of Agriculture.

"After populations spread northward through Pennsylvania, the ladybugs now invade homes in large numbers during the fall. Unfortunately, once inside they are unwelcome, as ladybugs have an unpleasant odor; stain walls, draperies and furniture; crawl on people; drop into food, and occasionally bite."

Ladybugs feed in trees and agricultural crops during the summer months, where they eat tiny plant-feeding insects called aphids. In the fall, when field crops die off and trees lose their leaves, the aphid populations drop dramatically, and the ladybugs have nothing to eat.

At this point, they leave the trees and fields and fly to buildings, where they congregate in large numbers on warm walls and rooftops. When temperatures drop at night, these beetles crawl into cracks and crevices, eventually getting into interior walls and attics.

"If you are prepared to act when the beetles begin their invasion, you may be able to keep them from coming indoors in large numbers," Wolff said. "Homeowners may be able to keep beetles from entering houses by sealing off cracks and crevices on the warm sides of their houses, and by applying the insecticide cyfluthrin to the exterior of the house, including the roof, when the lady beetles are moving from the trees and onto the houses."

Wolff added that this migration usually takes place on warm days in October, often around Columbus Day. An application of cyfluthrin will kill lady beetles as they crawl on the outside walls.

Research has shown that cyfluthrin acts as a repellent and may help to keep the ladybugs from collecting on houses.

For more information about the Asian lady beetle, visit www.agriculture.state.pa.us.

Kristina Watson is a spokeswoman for the Pennsylvania Department of Agriculture.

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