The Asian Lady Beetle

COLEOPTERA: COCCINELLIDAE:
Harmonia axyridis (Pallas)

Ladybugs have always been considered beneficial insects, worthy of protection. According to the Pest Profile in Pest Management, Oct. 1995, over 4,000 different ladybug species exist worldwide.

The Asian lady beetle is very common in eastern Asia where it is thought to have originated. Because it is weather-hardy and highly reproductive it was introduced into the United States for the control of orchard and field crop pests. Introductions into California, Texas, Mississippi, Louisiana, Maryland, Connecticut Georgia, Ohio, Pennsylvania and Washington have all been recorded. According to Lyon (1995), it was released in California as far back as 1916, and is a tree dwelling species.

It has now spread into nearly every state in the nation, as well as Canada. A number of common names have caught on in various areas of the country for this species of beetle, including but not limited to: Multicolored Asian Lady Beetle (because of variable coloration), Japanese lady beetle (because releases in some southern states were actually collected in Japan), Halloween lady beetle (because of the pumpkin color and swarming of the beetles near Halloween time), and its Latin name above (so that scientists can be sure that they are talking about the same species).

Pest control operators have been faced with a growing number of swarms during autumn that enter buildings and homes through cracks to overwinter within the walls. This bulletin summarizes identification, biology and habits, and recommended control measures.

Asian lady beetles are about 1/3 inch long by 3/16 inch wide, pale yellow to orange, and even reddish if older, with up to 19 black spots on the wing covers.

A black M-like shape usually is found over the platelet above the thorax Figure 1. The shape of this "M" can be variable.

According to Lyon (1995), the larvae are typical of most lady beetle larvae in shape and coloration, except that their abdomens are lined with tubercles or spines that are forked outward into a "Y" shape, Figure 2. The yellow, oval eggs are generally laid upright in clusters of about 20 on the undersides of leaves.

Biology and Habits

The cycle from egg to adult takes a little over a month, and longer during cooler weather. Eggs may hatch in 3-5 days, larvae may feed for about 2 weeks, and pupation lasts almost another week. Potter (1995) mentioned that they may pupate by attaching to vegetation or the exterior walls or foundations of buildings. Then adults emerge end can live up to three years!

There maybe multiple fife cycles per year. Lyon (1995) explains that females may overwinter unmated and will aggregate in a large swarm with males in the spring when it warms up. Main swarms occur in October and November to search for overwintering sites, and again in February and March during warm, sunny days to leave the protected nesting areas to mate and procreate. The larval and adult stages of most of these species will feed upon aphids, mealy bugs, and other serious plant Pests.

Populations thrive where food is plentiful such as in forested areas and parks. Asian lady beetle adults prefer to cluster on the sides of structures and eventually work their way in through cracks or natural breaks in windows, doors, foundations, or eaves. Large swarms typically fly above the tree tops and zero in on:

• Light colored buildings or rock outcroppings
• Highly illuminated or southwest-facing sides
• Buildings in poor repair close to trees and woods

Lyon (1995) reminds us that the beetles do not bite, sting, carry diseases or feed on clothing. They do not reproduce indoors. Although they occasionally deposit yellow string-like droppings on indoor surfaces, cause a yellow stain if crushed, and have a slightly undesirable odor, they remain beneficial insects.

Once indoors, they slow down into a hibernation-like mode, neither eating nor moving much until the first warm days of late winter or early spring. When they come to life, again in the spring is when homeowners really notice their presence. The beetles have simply forgotten how they got in. When clusters of several hundred to thousands appear in living rooms, bedrooms, or a kitchen it is hard not to grumble.

This reawakening may take place over several weeks, depending upon temperatures and population size. Since the beetles are attracted to light and warmth, they are drawn to windows and lights inside structures. Once trapped they will die, but they may temporarily cluster in the upper corners of living spaces.

Control Summary

The references cited herein recommend a number of measures to aid in controlling Asian lady beetles that invade structures. Major recommendations include but are not limited to:

• Educate your customers. Share the above information with them.
• Sweep up emerging beetles and deposit them outside if possible... vacuum if necessary each day of emergence using extensions and remove beater baron vacuum. Empty the vacuum bag outside since they may exit the bag once the vacuum is stored.
• For long-term control, seal the beetles out before they enter by caulking with a good quality silicone-latex caulk around all external cracks, pipes, doorways, vents, windows, etc.
• Install screening (20-mesh maximum) over attic and exhaust vents, and use door sweeps on all doors.
• Repair exterior screens.
• Since beetles are attracted to ultraviolet light, use of UV light traps may enhance attraction to collection devices during emergence.
• Spraying and fogging the living spaces offers only temporary relief and is not recommended. However, strategic aerosol injection of outer structural voids with synergized pyrethroids can reduce overwintering populations significantly.
• Foam weather-strip bases of sliding glass doors.
• Autumn exterior residual treatment of gaps around a structure may be effective if timed just prior to entry, i.e., late August to early September, and not after entry.

Remarks

The Asian lady beetle is here to stay. Although for the next few years their swarms may increase, natural enemies that keep the beetle in check will in time appear. In North Carolina, a tachinid fly parasite already controls about a quarter of all Asian lady beetles. So as other natural parasites, diseases, and predators build up on these beetles, we should see beetle numbers level off and then gradually decline. This beetle is not an endangered species. Reports indicate that like honeybees, the swarms on the sides of buildings or trees often leave in a few days and are best left alone.

References

Kramer, Richard D. 1995. Lady Beetles. Pest Management. pp. 33-4.

Lyon, William F. 1995. Multicolored Asian Lady Beetle. Ohio State Extension Fact Sheet HYG-2158-95. 2pp.

Potter, Michael F. 1995. Ladybug, Ladybug, Fly Away From My Home. Pest Control. August. Pp. 58, 62, 64, 66.

The information contained in NPCA's technical publications should not be construed as standards of the Association. The information describes methods and procedures that should be regarded as recommendations or optional guidelines. Each company or person using or distributing this publication is responsible for ensuring its accuracy and applicability at the time and under the circumstances used or distributed. This release is subject to periodic review and update by NPCA technical staff. This release was written by the NPCA Insect Control Committee.