Mike Lunsford: Asian lady beetles, our benevolent pests

The familiar feel of tiny feet on my neck inspired this tale about the Asian lady beetle, for as I finished off a bit of work at my desk a few days back, one of the little orange-brown pests decided to find its way under my collar and down my back. As I began to fumble and contort in search of it, I looked up to see a few more milling about on a window pane; it was hardly a surprise.

Described by Purdue entomologist Bob Bruner as “… one of the most useful insects, while being one of the most reviled at the same time,” the appearance of Asian lady beetles as we slowly turn the dial on the seasons is an annoyance that we should learn to simply endure. Although they probably would have found their way here one way or the other, the beetles were “introduced” to this country over a century ago, and they have made themselves right at home ever since.

“We intentionally introduced this insect in the early 20th century as a way to control other insects, and they did their job fairly well,” Bruner, 42, an “exotic forest pest specialist,” says.

“Overall, the beetle is a very active predator of pests, like aphids. There have been a few different intentional releases, but according to the USDA (the Department of Agriculture), we didn’t see consistent, established populations until they were found in Louisiana in 1988. The debate is still going as to whether their establishment is due to the intentional releases, or because they’ve been accidentally shipped like many other non-native insects. I’m guessing, due to the timing, that their spread is more likely due to human shipping activities than it is controlled releases.”

Intentionally established or not, Asian lady beetles — not to be confused with their relatives, what we call “lady bugs” — are here to stay, and one reason they seem to be persistently with us is they are perfectly designed by nature to resist predators. “Multicolored Asian lady beetles are non-native, which means none of the other animals in Indiana evolved to recognize them as food,” Bruner says. “The beetles also produce a bitter compound that can make them unpalatable to the predators that will try to eat them, and their bright colors act as a warning against potential threats.”

After realizing that my work space was quickly becoming the scene of a beetle prison break — it was a warm and sunny day — I first tried to pick them off books and window sills and lamp shades by hand, before depositing them outside. But as the day went on, I realized I had other things to do with my life, so I moved an old vacuum from our garage to my cabin and began sweeping them up a few at a time. Within a few hours, I was still annoyed but caught up in the thrill of the hunt. About the time I felt the beetles were gone, I’d soon see one trundling along a shelf or wandering across a picture frame. As the day cooled and grew dark, they stopped showing up.

Although these beetles tend to mount their greatest invasions on our homes in the autumn, heading indoors in droves to find cozier quarters for the coming winter, the exact opposite occurs as the weather warms in late February and early March; they emerge from their bunks beneath siding and in attics, most often wandering toward the light. In fact, their interest in warmth and light often pulls them out of hiding and into our living spaces at night as we click on lamps and sit in the glow of our televisions; a west-facing window in my cabin seems to be a favored spot year after year.

Not all Asian lady beetles are orange, or even have the spots we associate with them. They have a “tendency to have color morphs,” says Bruner. “That’s where members of one species can have several different colors or patterns,” he adds. Bruner also says that whether we like them or not, they do an amazing job of eating aphids.

Yet, they have a litany of irritating habits that make them less than perfect house guests. Bruner acknowledges that they can leave tell-tale stains on drapes and other fabrics, and, to some aroma-sensitive folks, they stink. More than one victim has told me an Asian lady beetle has bitten them, something I was trying to avoid as I stripped down to a T-shirt as I searched for my new friend.

Bruner suggests that the best way to keep the beetles out of our homes is to find the openings they are exploiting to get in. “Check all window screens, under eaves or other places that might have an easily-repaired opening, and make sure your doors are sealed properly.” Yet he acknowledges that often the little invaders simply hitch rides into our houses on our clothes or hair, but he doesn’t suggest spraying them with a pesticide.

“The best way to get the insects out of the house is to sweep them up. I wouldn’t spray for them as an insecticide is just as threatening to you as it is to them, can potentially harm pets, and the beetles are often secluded away where you might not reach most of them anyway. When these beetles live in our homes, they aren’t able to survive very well at all; they need to hibernate, and our homes don’t give them that environment. Save your money and just sweep them up,” Bruner says.

Which brings me back to my writing desk. With my trusty old vacuum on the floor nearby, ever ready to do battle, I spotted a beetle in a place where even a hose and attachment would do no good: it was doing its best to dogpaddle across the warm black pool of my coffee cup. A bit irritated, I opened my door and tossed the coffee and its occupant outside.

That’s when I noticed that a stink bug had landed on my shirt; the struggle goes on.