No, you aren’t seeing things. No, you don’t need to have your eyes checked. Although it does appear that your wall is shifting, that is simply an inordinate number of Asian lady beetles congregating for shared shelter. When temperatures start to drop during the fall, these speckled relatives of the more popular ladybug go searching for warm spots. Often times that happens to be a sunny spot in your home or office. While a nuisance, these beetles do not carry diseases harmful to humans, they do not reproduce indoors, and they do not feed on wood or clothing. Read on for some interesting facts about the Asian lady beetles.
Asian Lady Beetles Are Beneficial
The Asian lady beetle is native to eastern Asia and was released in the United States years ago to help control pecan aphids. Many scientists believe, however, that the releases were not successful and that the current multicolored Asian lady beetles were inadvertently introduced from an Asian freighter in New Orleans. Regardless of how they got here, gardeners and farmers are glad to have them and consider them one of the many beneficial insects. Along with our native ladybugs, the Asian lady beetles feed on aphids and other soft-bodied insects that damage plants and crops.
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Why Are They Crawling On My House?
In the fall, you may find large numbers of Asian lady beetles (often called Halloween lady beetle or Japanese lady beetle) congregating on outside walls, windows, and doors, especially on the sunny south and west side of buildings. Adults often cluster together in October and November to overwinter in sheltered locations, and when a few adults find a suitable spot, they release a chemical (pheromone) that attracts others to the same location, and they all begin to move to shelter. In the first warm days of early spring, these beetles are often seen during bright sunny days as they move from their sheltered spot to an outdoor habitat.
Vacuum Them Up To Prevent Staining
Asian lady beetles are reflex bleeders, which means when handled or disturbed, they ooze reddish blood from the joints of their legs. The blood also has a bad odor and will stain anything it comes in contact with. It is best not to sweep beetles off a wall or window frame, because this will cause them to bleed. Remember, Asian lady beetles are our friends, so do not reach for an insecticide in order to rid your home of this harmless nuisance. Your best option for removing the beetles is to vacuum them as soon as you see just one or two; remember, just a few can attract many others. Remove the vacuum bag after you have collected the beetles to prevent them from either crawling back out or dying, which will produce a bad odor. You can use a clean vacuum bag, collect the beetles, and then store the bag in a sheltered outdoor area. In the spring, the beetles will emerge from the bag and begin feeding on those pesky scaly insects and aphids.
Preventing Asian Lady Bugs From Entering Your Home
Seal Up Your House
One way to prevent these little crawlers from entering your home is to make sure all the openings and cracks near your doors and windows are sealed. Since these spotted bugs can get through a crack that is as tiny as one-eighth of an inch wide, it is important to use a sealant such as silicone caulk to fill in any small cracks or openings in your home.
Use a fine mesh on your windows, doors, and exhaust vents to keep them from getting through and into your home.
Do Asian Lady Beetles Bite?
If you handle and disturb a beetle, it may bite and draw a bit of blood. They can also cause inhalant allergies in some people. The allergies will clear up once the lady beetles are removed.
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- University of Minnesota Extension. Multicolored Asian beetles.
- Entomology at the University of Kentucky. Asian lady beetle infestation of structures.
- Nakazawa T, Satinover SM, Naccara L, et al. Asian ladybugs (Harmonia axyridis): A new seasonal indoor allergen. Journal of Allergy and Clinical Immunology. 2007;119(2):421-427. doi:10.1016/j.jaci.2006.11.633