This past week has brought out huge amounts of Asian Lady Beetles, also called ladybugs, lady beetles or ladybird beetles, which are a very beneficial group. They are natural enemies of many insects, especially aphids and other sap feeders. A single lady beetle may eat as many as 5,000 aphids in its lifetime. Many species of lady beetles are present in Oklahoma, and they are common in most habitats.
Adult lady beetles have very characteristic convex, hemispherical to oval-shaped bodies that can be yellow, pink, orange, red or black, and usually are marked with distinct spots. This is a type of warning coloration to discourage other animals that may try to eat them. Like many other brightly-colored insects, they are protected by an odorous, noxious fluid that seeps out of their joints when the insects are disturbed. The bright body coloration helps some predators to remember the encounter and avoid attacking insects with similar markings. Adult females usually lay clusters of eggs on plants in the vicinity of aphid, scale, or mealybug colonies.
The alligator-like larvae are also predators. They are spiny and black with bright spots.
Although they look dangerous, lady beetle larvae are quite harmless to humans. After feeding on insect prey for several weeks, the larva pupates on a leaf. Adults tend to move on once pests get scarce, while the larvae remain and search for more prey.
Some lady beetle species have several generations each year, while others have only one. During the summer months, all stages can often be found at the same time. Adults of some species spend the winter clustered together in large groups under leaf litter, rocks, or other debris.
While the beetles tend to be more attracted to lighter-colored buildings, illumination or brightness appears to be an even stronger attractant than color. For this reason, beetles tend to initially congregate on the sunnier (southwest) side of most buildings. Homes or buildings that are not brightly illuminated by sun, especially if shaded on the southwest side, are less likely to attract lady beetles.
During the 1960s to 1990s, the U.S. Department of Agriculture attempted to establish the Asian lady beetle to control agricultural pests, especially of pecans and apples. Large numbers of the beetles were released in several states, including Georgia, South Carolina, Louisiana, Mississippi, California, Washington, Pennsylvania, Connecticut and Maryland. No such releases were ever attempted in Oklahoma, and their occurrence here is probably due to northward migration from other Southern states. Some scientists believe that current infestations in the U.S. originated not from these intentional releases, but from beetles accidentally transported into New Orleans on a freighter from Japan.
Because the Asian lady beetle is a tree-dwelling insect, homes and buildings in forested areas are especially prone to infestation. Suburban and landscaped industrial settings adjacent to wooded areas have also had large lady beetle aggregations. Once the beetles land on the sunny side of the building, they attempt to locate cracks and other dark openings for hibernation sites. These locations may ultimately be on any side of the structure. Common overwintering sites include cracks and crevices around window and door frames, porches, garages and outbuildings, beneath exterior siding and roof shingles, and within wall voids, attics, and soffits. Structures in poor repair or with many cracks and openings are especially vulnerable to problems.
As spring approaches, beetles overwintering in and around structures will disperse outdoors to play an important role as beneficial insects. Lady beetles unable to find their way outside will eventually succumb to a lack of food and die.
As noted, lady beetles do not injure humans, nor can they breed or reproduce indoors like fleas or cockroaches. Nonetheless, some people will not tolerate insects of any kind in their homes. Hospitals, food processors, and similar hygienic establishments have zero tolerance for contaminants of any kind, including insects. Given these varying levels of tolerance, we offer the following management options.
The easiest way to remove ladybugs, once they are indoors, is with a vacuum cleaner. If you wish to subsequently release beetles outside, place a handkerchief between the vacuum hose and the dust collection bag to act as a trap. A broom can also be used to remove beetles indoors but is more likely to cause staining. (The orange-colored fluid that the beetles secrete when picked up or disturbed is harmless but will stain walls and other surfaces.)
Because the Lady beetle seeks out overwintering sites in the fall, exterior cracks and openings can be sealed as a long-term, preventive measure.
Adjust or install tight-fitting door sweeps or thresholds at the bottom of all exterior entry doors. Gaps of 1/8” or less will permit entry of lady beetles and other insects. Garage door bottoms should be fitted with a bottom seal constructed of rubber (vinyl seals poorly in cold weather). Gaps under sliding glass doors may be sealed with foam weather-stripping.
Seal utility openings where pipes and wires enter the foundation and siding, e.g., around outdoor faucets, receptacles, gas meters, clothes dryer vents, and telephone/cable TV wires.
Caulk cracks around windows, doors, siding, and facia boards.
Repair damaged window screens and install insect screening behind attic vents.
These practices will also help prevent entry of other pests, such as flies, mosquitoes, wasps, crickets, and spiders. Pest proofing further helps to conserve energy and increases the comfort level during winter and summer.
Indoor treatment. Insecticide foggers or sprays are generally not recommended for eliminating lady beetles indoors. Beetles need to be sprayed directly or have to crawl over treated surfaces in order for the insecticide to be effective. Such applications create pesticide residues on walls, countertops, and other exposed surfaces. A vacuum cleaner is more sanitary and effective. Attempting to kill overwintering lady beetles in wall voids is difficult and rarely justified. Large numbers of dead insects in these areas also may attract carpet beetles and other pests of food and fiber.