Clients soon will be calling about lady beetles congregating on the sides of homes and infesting buildings. This phenomenon has become an all-too-common autumn event throughout Kentucky and much of the United States.

The culprit is the Asian lady beetle, Harmonia axyridis, in search of protected places to spend the winter. In Kentucky, movement into buildings typically begins in mid-October, continuing through mid-November.

Detailed information on this perennial problem is contained in ENT-64, Asian Lady Beetle Infestation of Structures. Key points include:

1. Lady beetle flights are heaviest on warm sunny days when temperatures climb above 60 degrees F. They tend to congregate initially on the sunnier, southwest sides of buildings in mid-afternoon. Structures that are shaded and not brightly illuminated by afternoon sun are less likely to attract the beetles.
2. Once the beetles alight, they attempt to enter crevices and other dark openings in search of hibernation sites. These locations may be anywhere on the structure, but especially beneath exterior siding, around window and doorframes, soffits, fascia boards, and through weep holes and attic or crawl space vents. Sealing exterior cracks and openings with caulk, screening, weather stripping, etc., is the most effective long-term, prevention against beetle entry. (See ENTFACT-641 How to Pest-Proof Your Home.)
3. Once the beetles are indoors, the best way to remove them is with a vacuum cleaner. When brushed or handled the beetles often secrete a yellowish-orange fluid, making vacuuming a better option for indoor removal than brooms, mops, etc. Insecticides applied indoors tend to be ineffective and may stain or leave unwanted residues on walls, counter tops, and other surfaces.
4. While sealing exterior openings is the more permanent means of denying ladybug entry, pest proofing is time-consuming and impractical for many clients. If a household or business continues to be troubled by lady beetles, owners may want to enlist the services of a professional pest control firm. Some companies offer pest proofing services and many offer insecticide treatment of the building exterior, which helps to prevent pest entry. Fast-acting, “professional strength” pyrethroid formulations (e.g., Demand, Suspend, Talstar, Tempo) tend to be most effective, and can be applied around eaves, attic vents, windows, doors, underneath siding, and other likely points of entry. Homeowners insistent upon applying exterior treatments themselves will usually get the most for their efforts using over-the-counter versions of these products such as Spectracide Triazicide or Bayer Advanced Powerforce Multi-Insect Killer. Purchasing the concentrated formulations of these products that can be diluted will enable the homeowner to mix up and apply larger volumes of material with a pump-up or hose-end sprayer. In order to have any benefit, exterior treatments must be applied before the beetles enter buildings to overwinter.
5. When all else fails, customers should be reminded that lady beetle entry into buildings is a relatively short-term event which generally runs its course by mid-November. The beetles sometimes emit a foul odor, stain indoor surfaces, and occasionally give a “nip” if they land on one’s skin. They do not breed or reproduce indoors like fleas or cockroaches, and constitute a nuisance mainly by their presence.

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