What Attracts Asian Lady Beetles to Your House?

The most-cited peer-reviewed study on this exact question — Nalepa, Kennedy & Brownie (2005), published in Environmental Entomology — tested what actually draws Asian lady beetles to land on a surface at overwintering time. The result: beetles preferentially land on and near high-contrast, dark-on-light linear features — the seam where trim meets siding, a gutter line, a window frame, an architectural shadow — not simply on bright, light-colored, or reflective surfaces as the older belief held. The paper explicitly states the beetles are "not visually attracted to the color white per se," and calls into question the earlier assumption that shiny, reflective walls are themselves the draw.

That's a real, sourced correction to a common belief. It's also not what our own old page implied by leaving the mechanism unstated — readers left to fill in the gap usually land on "it's warm" or "it's the porch light," and the controlling study says neither is the operating cue for where a beetle lands.

None of this erases warmth from the picture; it just moves warmth to a different part of the explanation. Extension sources describe Asian lady beetle flights to buildings as happening on warm, sunny afternoons — often specifically after a cold snap — because that combination of temperature and light triggers the flight behavior in the first place. So warmth gates *when* the beetles take flight to look for overwintering sites; it is not what tells an already-flying beetle *where* to land. Once inside a wall void or attic, they don't feed and don't reproduce there — they're simply waiting out the winter, and midwinter heating can rouse dormant individuals into living spaces, which is often mistaken for a fresh infestation rather than the same population waking up.