ASIAN LADY BEETLES

Yes, New Yorkers, they’re here! This new Asian import is now widespread throughout most of the Empire State, but with most reports concentrated in the eastern and southeastern areas. A little more than a year ago we first heard about the spread of the Multicolored Asian Lady Beetle (scientific name: Harmonia axyridis) from the deep South into the northern states. By October, 1993, homeowners in Virginia, West Virginia, Kentucky, North Carolina, Pennsylvania, and Ohio were virtually inundated by this new exotic introduction. Homes and outbuildings were being overrun by hundreds, and even thousands, of these brightly colored day beetles. Apparently, this same phenomenon is happening right here in New York. Although this beetle is a predator of pest aphids on crops and ornamentals, and so regarded by many as a beneficial insect, its presence in large aggregations outside and inside homes in the fall and winter (on exterior and interior walls, on doors, ceilings, windowsills, inside window screens, on porch decks, etc.) has caused homeowners great anguish and much concern.

This is what we currently know about the Multicolored Asian Lady Beetle… Lady beetles of the genus Harmonia are found in Asia and Australia and prey on aphids, psyllids, and scale insects. The Asian Lady Beetle is widely distributed in Asia, being recorded in Japan, Formosa, China, Korea, Manchuria, and southern Siberia. This species is found primarily in orchards and forest habitats. It is found in various trees, including maple, walnut, willow, and oak. The species exhibits numerous color phases, is extremely prolific, and is capable of living up to three years.

Historical Occurrence and Releases: Several attempts were made to intentionally introduce the Asian Lady Beetle into North America in the past: in California in 1916, and in 1964 and 1965; and in a dozen eastern and southeastern states and Nova Scotia during the period 1978-1982, and in 1985. Establishment of the beetle was not reported until 1991 in Louisiana and Mississippi. Since then, we have seen a mass movement of beetle populations from the South into the North. It has been suggested that when there is an abundance of food (aphids, etc.) and no competition, populations of this exotic lady beetle explode. Apparently, conditions have been such that this situation has occurred in the northern states.

Identification: The beetles are oval, convex about 1/4 inch long, 3/16 inch wide, and highly variable in color, ranging from a basic red and orangish form to a very dark, sometimes black, appearance. The wing covers of the yellow or orange colored specimens usually are spotted with black. These spots also vary in size and number. The head is usually concealed from above and the whitish pronotum (the area between the head and the wing covers) usually has a black marking resembling an "M".

Seasonal History and Habits: During cool spring weather, about 36 days or longer are required for a typical life cycle from egg to adult to be completed. In general, eggs hatch in 3-5 days. The larvae feed voraciously for about 12-14 days on aphids, scale insects, and other soft-bodied invertebrates. The pupal stage lasts about 5-6 days. After emergence, adults are capable of living as long as 2-3 years under optimal conditions. Female beetles, it is thought, overwinter unmated, with the majority of the population mating later in the spring. Most beetles are reported in October and November when they congregate in sheltered (usually indoors) overwintering sites and again in February and March on bright warm, sunny days when they are seeking outdoor habitats. When indoors, they commonly cluster together in a corner of the ceiling and wall.

Control Measures, Disposal, and Recommendations: The use of insecticides is not recommended for control of unwelcome populations of this lady beetle. It is best to remove beetles alive from the home by using a broom and dust pan, or vacuuming them up and releasing them outdoors. If more beetles find their way back into the house, most likely they are entering around windows, doors, siding, utility pipes, etc. Therefore, attempt to seal all obvious cracks and openings with a quality silicone or silicone-latex caulk. Replacing damaged door and window screens can also help.

Outlook: Because of its effectiveness in helping to control pest aphids on ornamental trees and shrubs, fruit trees, pine trees, and numerous crops, the Asian Lady Beetle is a welcome addition to the plant life of most states. Obviously, large populations will eventually decrease as the lady beetles fall prey to native, natural enemies.

Find out more:

Asian Lady Beetle (Lady Bug)

Multicolored Asian Lady Beetle

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