Ladybugs or lady beetles are everywhere. They are beneficial insects in the outdoors but can become a nuisance pest when they invade our indoor spaces. Native ladybugs overwinter in outdoor sites while the Asian lady beetles hibernate indoors.
Asian lady beetles enter homes and shelters in alarming numbers in the fall. They are aggravating as they are attracted to lights and windows inside our homes. The warm weather we have recently experienced continues to have ladybugs actively searching for indoor shelter to hibernate until they will emerge once again in the spring.
The multicolored Asian lady beetle is native to Asia. In its native habitat, it overwinters or hibernates in the cracks and crevices in cliff faces. In the absence of cliffs, they seek shelter in buildings.
They are considered nuisance pests due to the large numbers that sometimes gather on our structures until they eventually locate a crack or opening allowing them indoor access. Once a desirable location is secured, a pheromone is released that attracts other multicolored Asian lady beetles. While a few may be tolerable, hundreds to thousands are problematic to the homeowner.
They may overwinter under roof shingles, under siding, attics, porches, door or window frames. They mass together and invade homes searching for winter shelter. Once inside, due to warm indoor temperatures, they leave their overwintering site and invade our spaces – flying about into food, drinks, and anything in their path.
While they are not naturally aggressive, they will bite humans although they do not draw blood or break the skin unless it is tender skin.
They may cause inhalant allergies in some individuals. They do not sting but a stinging feeling and contact dermatitis may occur in those allergic to the fluid the beetles secrete.
A yellow-orange fluid, which they exude, may stain any surface that it contacts. This defense mechanism is called reflex bleeding. The odor is offensive; care must be taken to not crush or injure the lady beetles to avoid both the smell as well as the stains.
They do not carry disease organisms.
They do not reproduce in structures but mate in the spring after they depart from their hibernation sites.
They do not eat human food, wood, or other items. While overwintering, they rely on stored fat or eat aphids or other insects which have soft bodies.
Asian lady beetles are truly multicolored as they have many color variations – yellow, orange or red with or without black spots. The number and size of the spots also vary.
Asian lady beetles are approximately 0.2 to 0.3 inches long with a round to oval dome shape.
Since they are beneficial predators, which feed on aphids and scale insects that harm our garden and landscape plants, we do not want to destroy them but prevent them from entering our homes. Management is crucial to controlling the population both prior to and after entering the structure.
Prior to ladybugs seeking shelter, cracks around any opening should be sealed with weather striping or caulk. Damaged door or window screens should be repaired. Entrance doors should have thresholds installed. Attic and exhaust vents should have screen wire applied to prevent entry.
Once the pests have entered the home, there are several methods the homeowner may employ for control.
If the numbers are small, they may be gathered by using duct tape or another type of tape to stick to the insect prior to discarding them.
Vacuuming is another solution particularly if the numbers are large. Once vacuumed, remove the bag and store it until spring. Another vacuuming method is to put a stocking in the wand secured by a rubber band. After vacuuming the beetles into the stocking, add a damp cloth (for moisture) and store the stocking, with the rubber band securing the opening, in an unheated area and release them in the spring.
Pesticides are also available but are ineffective unless the insects crawl through them since lady beetles are generally hidden in difficult to reach areas. Always read and follow label directions whenever using pesticides.
While large numbers of Asian lady beetles indoors are troublesome, they are extremely beneficial out of doors as they feed on aphids and scale insects keeping these difficult pests in manageable numbers on our garden and landscape plants.