Asian beetles generally survive cold winters by seeking sheltered spots and using natural “antifreeze” in their bodies. They do not die off simply because the outdoor temperature drops; only prolonged exposure to extreme, unsheltered cold (below about –10 °C to –15 °C) will kill many of them.

How Asian Beetles Overwinter

Asian beetles (often called lady beetles) look for tight cracks and warm cavities as temperatures drop in autumn. Once inside walls, attics, or under tree bark, they enter a resting state known as diapause. In this state, their metabolism slows dramatically, meaning they use very little energy and can survive long periods without food.

Cold Survival Mechanisms

To avoid freezing solid, these beetles produce natural chemicals in their blood called cryoprotectants, similar to antifreeze. These compounds lower the freezing point of their body fluids. They may also generate antifreeze proteins that prevent ice crystals from forming in their cells.

Factors Influencing Winter Mortality

• Temperature extremes – Sustained cold below about –10 °C to –15 °C can overwhelm their defenses if they lack good shelter.
• Shelter quality – Beetles hidden deep in insulated walls or under tree bark fare much better than those in unprotected crevices.
• Humidity – Very dry conditions can dehydrate them during diapause; too much moisture can promote mold and disease.
• Energy reserves – Beetles that entered diapause late in the season may have less stored fat and die sooner in severe cold.

What This Means for Homeowners

Because these beetles survive typical winter lows, especially in places like Nashua, New Hampshire where winters often reach only –5 °C to –10 °C, you’ll still find them alive in wall voids or attic spaces. The best way to reduce their numbers in spring is to seal entry points—caulking cracks around windows, doors, and eaves—to prevent them from getting inside in the fall.