Mild summer might have led to swarms of Asian lady beetles

photo Asian lady beetles have appeared all over the Chattanooga area, including this house in St. Elmo.

MEET THE BUGOrigin: Native to Asia, in the U.S. since as early as 1916. First populations found in 1988 around New OrleansAppearance: Varying shades of orange and red and up to 19 black spots, more than native beetlesCharacteristics: Voracious appetite for aphids, prolific reproduction. Looks for shelter during cold weatherImpact: Overall, beneficial for environment. Major negative is intrusion into human structures.Source: USDA Agriculture Research Service, University of Tennessee Agriculture Extension Office

Jon Moss read through a line of frantic Facebook comments Tuesday afternoon, sniggering to himself.

Ladybug infestation. Pfft.

"I thought 'Hmm. Our neighborhood got skipped by this,'" he said.


Moss walked outside his home that evening, and there they were -- polka-dotted and in various shades of orange, a patchy mural of presumed ladybugs hanging on the south wall of his Big Ridge home. He'd never seen anything like it.

He cranked up the water hose and went to work clearing them away. The plan backfired.

And he had left the garage door up.

"They were coming in biblical proportions," he said.

All over the interior walls of the garage. All over the car. Kids are unsure what to think of the little bugs.

"I don't need this," Moss said to himself.

Jon Moss, meet the multicolored Asian lady beetle. Multicolored Asian lady beetle, Jon Moss.

Doubtless, you've met before, you just didn't know it.

It's another accident of international trade. In the 1990s, Asian lady beetles likely stowed away in cargo to America. Here, conditions have allowed the beetles to thrive.

They are cousins of the lady beetle -- or ladybug -- of North America and have been around in force since the late 1980s. And this year, swarms of them have been spotted all around the greater Chattanooga area.

Frank Hale, entomologist with the University of Tennessee Agriculture Extension Office, said it's likely the clouds of beetles are occurring because Tennessee never saw an extended period of hot weather back in the summer, and that allowed aphid populations to go unchecked. Aphids -- crop-munching little insects -- are the single food source for lady beetles, Asian and native alike.

More aphids, more aphid predators -- more lady beetles. More swarms. Natural, Hale said.

Native versus Asian lady beetles

North American and Asian lady beetles typically look a lot alike. As a rule of thumb, the Asian beetle is usually a lighter shade of orange and has more spots, Hale said.

"They're related, but they evolved on a different continent," Hale said. "That makes them look different. Anybody can see [the Asian beetles] have more spots."

More spots and either bigger appetites or bigger dreams, he said. The Asian lady beetle population "exceeds all other lady beetle species combined."

They out-eat American ladybugs. And reproduce like crazy.

As a result, Hale said, the Asian beetles are displacing their American cousins, literally eating them out of house and home.

Why they invade human structures

Like hundreds of folks around the country, this week Moss experienced the outcome of some unseen hard-wiring in the Asian lady beetle that causes it to seek structures for shelter when temperatures start dropping.

Swarming is part of the beetles' natural behavior. They do it when it's time to find a place to stay the winter.

Swarming isn't unique to the Asian beetles. Swarming to human structures is.

"There's something that triggers in them to go to vertical structures" to survive winter's cold temperatures, Hale said.

A vertical structure like a home, complete with heating, is a real find for the beetles. They are cold-blooded, and Hale speculated that swarming to human structures mimics a natural behavior. Perhaps back in Asia, he said, the beetles crawl into cliffs and enter a pseudo-hibernation during cold weather.

During warm months, the beetles hang around vegetation and have little reason to approach humans. After all, lady beetles have nothing to eat in a human home. Most of those that do get into a human structure will stay too warm to sleep off the winter and will die, cutting short their one- to three-year lifespan.

To deal with lady beetles indoors, Hale advised taking a vacuum to them, then dumping the collection.

The other key is sealing up the holes where the bugs came in. Hire a carpenter instead of a pest controller, he said.

The Asian lady beetles are harmless and can also be caught by hand, with patience and the willingness to ignore the stink they emit when agitated or smashed. Otherwise, they're simply a nuisance. They will not damage home structures or lay eggs inside.

"I'm not panicked about it," Moss said. "They're not harmful. They're just annoying."

Contact staff writer Alex Green at or 423-757-6731.