In the fall, large numbers of lady beetles (ladybugs) may be found around homes and other buildings in South Carolina. Some residents have report thousands of these beetles congregating on outside walls, windows, doors, porches and decks, especially on the sunny south and west side of buildings. These beetles can get indoors and may become a serious nuisance. Researchers believe that mild summers with high populations of aphids, which lady beetles eat, will often result in large populations.
The beetles found around most homes are known as the multicolored Asian lady beetle. They have also been called the Halloween lady beetle and Japanese lady beetle. Multicolored Asian lady beetles are oval, about 1/4 inch long, 3/16 inch wide, yellow to orange to red colored and may or may not have black spots on their bodies.
Adults often cluster together in October and November to overwinter in sheltered locations. When a few adults find a suitable spot, they release a chemical (pheromone) that attracts other multicolored Asian lady beetles to the same location. Then they all may begin to move to shelter. In February and March these beetles are often seen again during bright, warm, sunny days when they attempt to get out of a sheltered spot, such as a house, for the outdoor habitat.
These beetles do not carry human diseases, nor feed on wood, clothing or food. Also, they do not reproduce indoors. But there can be a lot of them.
Occasionally, the beetles may bite and can draw blood on tender skin. They may cause inhalant allergies in some people. These allergies clear up once the lady beetles are removed. Some people are sensitive or allergic to the fluid that lady beetles secrete, which can cause contact dermatitis and a stinging sensation.
In spite of troublesome, annoying populations, these insects are considered very "beneficial" to agriculture. They feed on harmful aphids and some scale insects associated with trees, shrubs, bushes, low growing ornamentals, roses, wheat, cotton, tobacco and other crops.
Numerous attempts to introduce this valuable predator to the United States were made by the United States Department of Agriculture between 1977 and 1981. Releases were made in Connecticut, Delaware, Georgia, Louisiana, Maine, Maryland, Mississippi, Ohio, Pennsylvania, Washington, and the District of Columbia. Extensive sampling was done for several years at each release site and no beetles were found until 1988. The first recovery was in Abita Springs, Louisiana. Because of the long period of time between the releases and the first recovery, scientists believe that the USDA releases were not successful. The current multicolored Asian lady beetles are believed to have been accidentally introduced from an Asian freighter in New Orleans.
To reduce these beetles in and around homes, vacuuming is generally the best method. These lady beetles are reflex bleeders. When handled or disturbed they ooze reddish blood from the joints of their legs. The blood also has a bad odor. The beetles can also be swept up, but this will cause them to bleed. The blood can also cause a stain on anything it comes in
contact with. It is important to vacuum the beetles as soon as possible, because a few can attract others. The vacuum bag should be removed from the vacuum immediately after the beetles are collected. If left in the bag, they may crawl back out or die and produce a foul odor after a few days. Some individuals choose to release the beetles away from their homes where they can overwinter in natural areas and benefit growers during the following spring. If a clean vacuum bag is used, it can be stored in a sheltered area outside. The beetles will then emerge from the bag in the spring and begin to feed on aphids and scale insects.
The best defense against invasion by the multicolored Asian lady beetle are preventive measures. Caulk or weather strip exterior cracks and other openings these beetles may use to enter buildings. Check lap siding for any large cracks and seal if found. Damaged screens on windows, doors and attic vents should also be repaired. This can be a major task since the beetles can enter a relatively small opening.
Insecticides are not recommended, unless the temporary annoyance of these beetles can no longer be tolerated. Sprays may provide some relief if applied immediately around outdoor locations including windows, doors, vents and eves after the first beetles appear inside the home. Many insecticides are labeled for use by homeowners. Products can be purchased at hardware and discount stores. Before using any pesticide, always read the label and follow directions and safety precautions.
Finding multicolored Asian lady beetles outside your home does not mean they will automatically move in to spend the winter with you. There have been many reports of lady beetles leaving on their own after a few days or weeks.