Ladybugs can be a nuisance, but they are good for us as well

Published 4:47 pm Friday, February 3, 2017

By Ty Torrance

Large numbers of lady beetles (ladybugs) infesting homes and buildings in the United States were first reported in the early 1990s. Ladybugs are normally considered beneficial since they live outdoors and feed on plant pests.

The Asian Lady Beetle, Harmonia axyridis (Pallas), is relatively new to this country. The beetle is native to Asia (e.g., China, Russia, Korea, Japan), where it dwells in trees and fields, preying on aphids and scale insects. The first field populations in the United States were found in Louisiana in 1988.  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.

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Adult Asian lady beetles are oval, convex, and about 1/4-inch long. Their color can vary widely from tan to orange to red. Most beetles have a small, dark “M” or “W”-shaped marking on the whitish area behind the head.  Larvae complete their development on plants where their primary food (aphids) is abundant. The average time from egg to adult is about one month and there are multiple generations per year. Individual beetles can live up to three years.

As autumn approaches, the adult beetles leave their summer feeding sites in yards, fields and forests for protected places to spend the winter. Unfortunately, homes and buildings are one such location. Studies have shown that Asian lady beetles are attracted to illuminated surfaces. They tend to congregate on the sunnier, southwest sides of buildings illuminated by afternoon sun.

Unlike some household pests (e.g., fleas and cockroaches), they do not reproduce indoors — those appearing in late winter/early spring are the same individuals that entered the previous fall. Lady beetles do not attack wood, food or clothing. Besides being a nuisance, the beetles emit an acrid odor and can stain surfaces with their yellowish secretions when disturbed (volatile compounds used in defense against bird and other vertebrate predators).

The best control options available are actually exclusion or prevention.  Adjust or install tight-fitting sweeps or thresholds at the bottom of exterior doors.  Install weather-stripping around other parts of the doorframe. 

Seal utility openings where air conditioner pipes, phone, cable TV and other wires enter the foundation and siding.  Caulk around windows, doors, siding and fascia boards. 

Even after all of this preparation, it is possible that you will still have unwanted lady beetle visitors.  Your best choice (basically your only choice) now is to vacuum them up.

Make sure you take your vacuum bag out soon after, or they can crawl out and bother you again.  Although this insect can feel like a nuisance, try to think about all of the good it is doing by eating the pests on our agricultural crops, home gardens, and landscape plants.

If you have any questions about this article, please give the Extension office a call at (229) 248-3033.

Citations: University of Kentucky Extension, University of Georgia Extension.