Complaints About Lady Beetles

One lady beetle is cute. But a dozen feels like an infestation. When the cooler months set in, North Carolina State University entomologist Mark Waldvogel starts fielding calls from people complaining about the polka-dotted red beetles on their windows, plants and furniture.

“I’ve had people threatening to send me vacuum cleaner bags full of lady beetles,” he said.

Escaping the cold

The species of lady beetle we’re used to seeing is originally from Asia (although we do have a native ladybug), and was deliberately released by the United States Department of Agriculture to control aphids. And like ladybugs, lady beetles escape the cold by tucking themselves into crevices on rocks and tree bark. But in urban areas, houses are an attractive alternative. They wriggle through weather stripping around windows or cracks in the wall. Then, lady beetles snuggle in groups to hibernate for the winter.

But on warm winter days, they often rouse themselves. “If you see them in your house during the winter, it’s likely they’ve already been there since the fall and a warm day has made them more active,” said Waldvogel.

Lady beetles are attracted to light

Waldvogel says lady beetles are attracted to light-colored, flat surfaces like windows.

“There’s been a lot of research showing that lady beetles have pretty good eyesight,” he said. “They see contrasts well, so they’ll notice the shutters around the window.”

Southeast-facing windows are particularly attractive, because they warm faster and brighten up first in the morning.

Getting rid of lady beetles is not easy

Waldvogel often has to disappoint callers determined to rid their houses of lady beetles. He said trying to spray each lady beetle with pesticides isn’t practical or healthy, and light traps aren’t consistently effective. Squishing a lady beetle might not be a great idea either. Lady beetles produce defensive chemical secretions that stain, and sometimes cause allergy-like reactions in people.

But if a lady beetle is active in the winter, it will likely die without a supply of aphids (their main source of food) to eat. Sometimes lady beetles will land on people and test them with a nip (Waldvogel said entomologists avoid the word “bite”). But lady beetles don’t want to eat you, said Waldvogel. "They aren’t stupid. It’s not as if they think you’re a giant aphid.”

Keeping your house sealed tight against lady beetles (and cold weather) seems to be the most effective strategy, said Waldvogel. If they survive the winter, lady beetles will leave the house in the spring to lay their eggs on the underside of leaves.

“Once they are outside, we advise people to leave them alone,” said Waldvogel. “They’re doing you a favor by eating all the aphids.”