Cool Critters: That’s no lady (bug). The lookalike lady beetle is as helpful as it is harmful

The ladybug that slipped into your home to stay warm for winter is no lady and no bug.

Instead, it is likely the multicolored Asian lady beetle. The small, roundish insect with black spots is often confused with the native ladybug. And though they look alike, belong to the same insect family and eat pests in our gardens, the Asian lady beetle, unlike our native ladybug, is a pest itself.

As winter approaches, our native ladybug is nestled under loose soil or leaf litter or lodged between cracks in tree bark. Meanwhile, the Asian lady beetle prefers indoor lodging.

Scientifically known as Harmonia axyridis, it enters garages, porches and homes when the weather turns cold, Richard Zack of Washington State University said.

Native to eastern Asia, the insect was introduced into the United States to naturally control destructive insects such as aphids that threaten gardens, agriculture crops and landscape plants, he said.

“We did it on purpose,” he said.

Decades later, its population is booming.

A “mixed blessing” is how the U.S. Department of Agriculture describes the insect’s widespread presence today. More voracious than the native ladybug, it eats up to 65 aphids each day, according to the USDA. Because aphids feed on everything from lettuce, apples and potatoes to roses and marigolds, H. axyridis is a summertime friend. In winter, however, it can turn into a foe.

Two Asian lady beetles on the carpet are cute. A couple of small, colorful insects covered with polka-dots – what’s not to like? But a dozen or more of them clustered in a corner or on a window feels like an infestation.

When the insects congregate in large groups, “they become pests,” Zack said, adding that in some regions of the country, hundreds if not thousands of them have been documented inside people’s homes.

Here in the Inland Northwest, they typically appear in small numbers, he said. The insect is more of a nuisance in Western Washington, where several large accumulations have been reported over the years, he added.

Both the native ladybug and the nonnative H. axyridis are technically not bugs but beetles due to their chewing mouth parts and hard wing covers, according to the Entomological Society of America.

Even so, there are ways to tell the two apart. The ladybug is typically lollypop red, while the Asian lady beetle is a more muted red, orange or even yellow. Also, the lady beetle’s body is slightly larger and less circular than that of the ladybug. Additionally, it has a black “M”- or “W”-shaped mark where the head meets its body.

Should you find a few Asian lady beetles in your home, keep in mind that they don’t reproduce indoors. Nor do they chew wood like termites – they simply hang out. Then, come spring, they’ll return outside in search of aphids, according to the USDA. But if you can’t tolerate having these wintertime guests, “sweeping and vacuuming are effective methods for removing the lady beetles from living areas,” the agency states.

To keep them from entering your home in the first place, consider sealing your home with caulk or insulation foam to close exterior cracks and gaps around windows, door frames and outdoor light fixtures, Washington State University Extension advises.

But hey, it’s mid-November, which means these ladybug lookalikes are already indoors. With infestations galore in parts of the South, the folks at Mississippi State University Extension offer this guidance:

“It is not advised to seal off cracks on the exterior of the house this time of year because that would only trap the beetles inside,” they say.