Halloween might be over, but the swarms of multicolored, spotted “ladybugs” this fall can look like a scene from a horror movie. Illinois residents might have noticed an uptick in these harmless insects congregating in doors and windows, who search every fall for a warm place to spend the winter. They’re actually not ladybugs, but multicolored Asian lady beetles, an invasive species identified by the dark-colored “M” or “W” on their heads depending on the direction you’re viewing them. People’s homes make the perfect, cozy environment for the insects to hibernate. They’re even known as the Halloween beetle because of their annual autumnal journeys. The first cold snap of the season is a warning signal to the beetles. Then, a sudden warm day drives their metabolism and gets them moving faster to find a warm home. Last week’s warmer temperatures could be why Illinois residents are seeing more beetles this year than before, said Tom Tiddens, plant health care supervisor at the Chicago Botanic Garden. “It’s a good day for them to rally,” Tiddens said. Native to Asia, these beetles congregate on sunny, bright surfaces like windowsills and rain gutters. In their home ranges, they spend winters on south-facing cliffs that get a lot of sun. Experts recommend caulking, taping or sealing around possible entrances to deter not just Asian lady beetles, but also stink bugs and box elder bugs seeking a winter home. Although they’re seen as pests once inside homes, beetles aren’t dangerous to people, pets or the building structure. They don’t breed or lay eggs inside. But think twice before smashing them because they can release a foul smell, said Jennifer Rydzewski, an insect ecologist with the Forest Preserve District of DuPage County. “That odor can attract even more insects to join the indoor party,” she said. It’s a defense mechanism that can leave behind a yellow stain on surfaces, too. You can vacuum up the beetles, experts said. But be sure to empty it quickly due to allergen and odor buildup. Asian lady beetles were introduced in California in 1916 as a way to control aphids, small sap-sucking insects, feeding on pecans, according to the Illinois Extension office. And once released, they were here to stay, Tiddens said. “They’re good bugs working for us most of the summer,” he said. “They’re kind of on my payroll.” One adult lady beetle can feed on over 60 aphids a day that otherwise harm garden plants and crops. Tiddens has noticed more beetles this season, which he credits to a combination of the unusual warmth and an active year for aphids. “Just by having a good food source, these (lady beetles) can be prolific,” he said. But Ken Johnson, a horticulture educator with the Illinois Extension, said these beetles are a “double-edged sword.” They can outcompete native ladybugs, which is one reason for their population decline in the last few decades. Asian lady beetles often prey on the eggs of native ladybugs. There’s been some evidence that this loss leads to declines in other insect populations because complex species interactions get thrown off balance. The beetles sometimes feed on fruit, too. It’s a problem in wine production where if the beetles get crushed with grape clusters, the wine might taste a little off with what’s called ladybug taint, Johnson said. Nonetheless, Tiddens doesn’t consider them pests, just a little misunderstood. “I think for the most part, it’s a critter not to be too worried about,” he said. Here are some tips for managing lady beetles and other warmth-seeking insects from the Forest Preserve District of DuPage County: Use a silicone-latex caulk to seal cracks around door frames, windows and other possible entrances. Repair tears or replace screens on doors and windows. Use less attractive light bulbs with a yellowish hue. Turn off unnecessary lights at night indoors and outdoors. If in your home: Attempt to isolate that room by closing it off from other areas of the home. Use a vacuum cleaner to suck up the live or dead insects or sweep them into a container. Empty the vacuum into a bag or container, seal it and place it in an outdoor trash can or empty it outside. Continue cleaning the area every day or every other day to eliminate the remaining insects.