Asian lady beetles may create nuisance with "swarming behavior"
COLUMBIA — With colder weather upon us, mid-Missouri residents may start to notice an array of brightly colored, domed-shaped beetles lurking in the corners of their homes.
But have no fear — these pests are harmless. They’re the Asian lady beetles, and like many other insects, they’re simply searching for a sheltered place to escape the harsh conditions of the upcoming winter months, experts say.
Scientists call them the multi-colored Asian lady beetles. The U.S Department of Agriculture introduced this native of Asia into the United States in the 1970s as a control agent for the growing population of aphids and scale insects. It was later found in Missouri in 1993.
The Asian lady beetle is about a quarter-inch long, ranging in color from bright red to orange-yellow. Some have up to 19 spots, and some have no spots at all. Many of them have an M-shaped mark slightly behind their heads.
The Asian lady beetle is often mistaken for other beetle species in the insect family known as the lady beetle or lady bugs, said Rob Lawrence, a forest entomologist with the Missouri Department of Conservation.
The Asian lady beetle’s swarming behavior makes this species more of a nuisance, Lawrence said.
“While many lady beetles often have this congregating swarming behavior, the multi-colored Asian lady beetle does it in large numbers and often poses a larger nuisance due to the fact that they are often attracted to buildings and homes,” he said.
In their native Asian habitat, the lady beetle often found refuge in the vertical shafts of cliffs to escape the harsh conditions of winters. In Missouri, the vertical surfaces of many homes and other buildings mimic that natural environment.
“When lady beetles come into homes they’re not necessarily looking for warmth, because if they are warm all winter they would burn through their fat reserves and energy storage,” Lawrence said. Instead, they look for sheltered places like attics and wall cavities, which are still cool but don’t have the big fluctuations.
The beetles often enter a home through small gaps and crevices in the foundation.
“There are always a few reports that they do bite, but although they have biting mouthparts they are not harmful to people or animals,” Lawrence said. They don’t carry any diseases or reproduce in the winter months.
According to conservation department website, farmers and gardeners like the Asian lady beetle because it preys on aphids and other plant-destroying insects.
To combat the Asian lady beetle, the department recommends:
- Seal cracks around all major entryways, such as doors, windows and utility pipes.
- Check all windows for proper installation or screen tears.
- In extreme cases, consider careful use of an insecticide.
If you have already started to notice these small colorful pests creeping in the corners of your home, don’t fret. There are many ways to properly dispose of them.
The most common is to sweep or vacuum them up, but be aware that they often release a stink that many homeowners find hard to eliminate. They can also leave behind a stain.
Lawrence and other entomologists urge homeowners to remember that the beetles are important to the evolutionary cycle of the insect world. So next time you see a swarm of lady beetles hiding in the corner of your home, try to release them back into the outside world, they recommend.
For more information on the Asian lady beetle go to to the University of Missouri Extension website.
(Editor's note: This story's headline has been updated to correct a misspelling.)