This winter has been brutal with its cold, ice and snow. While each winter has its own personality, this one has been particularly brisk. We've had several mild winters in recent years, and nothing like the current deep freeze in a very long time. This year, the biting cold and ice feel almost corrective, as if nature is taking a long, bracing breath to let us know she's here.
In moments like this, I hope that the bitter cold is doing more than numbing our fingers and making it hard to feed the cattle. I cross my fingers and wonder if it might also be thinning out the ranks of the insects that have plagued our homes, gardens, and forests.
Stink bugs, spotted lanternflies, and other invasive pests have become unwelcome fixtures in Virginia. Could a hard freeze help eliminate these pests?
I went looking to see what I could find out.
Basically, extreme cold can kill bugs, but the story depends on the species, the timing, and the way each insect has adapted to survive winter.
The Limits of Insect Toughness
Most insects survive winter by entering a state called diapause. This is a kind of suspended animation that slows their metabolism and helps them conserve energy. Many also produce natural antifreeze compounds that keep their cells from rupturing in the cold. But these adaptations have limits. Every species has a “lethal temperature threshold,” the point at which cold overwhelms their defenses.
For the brown marmorated stink bug, which showed up in Virginia about 20 years ago, that threshold is surprisingly high. Research shows that prolonged exposure to temperatures below 14°F (–10°C) can kill a significant portion of the population. A deep freeze that lasts several days can reduce their numbers, especially if it arrives suddenly before they’ve fully acclimated.
The catch is that stink bugs often overwinter inside human structures. They're in our attics, wall voids, barns - basically anywhere temperatures stay warmer than the outdoors. The ones tucked into your siding will likely survive; the ones sheltering in leaf litter or tree bark may not.
The spotted lanternfly, a far newer invader, has a different vulnerability. Adults die off each winter regardless of temperature, but their egg masses are the real concern. Studies suggest that lanternfly eggs begin to suffer mortality when temperatures drop below 10°F (–12°C), and extended cold can kill a large percentage.
Because lanternflies lay eggs on exposed surfaces such as trees, rocks, firewood, and outdoor equipment, they are more at the mercy of the weather than stink bugs. A deep freeze can meaningfully reduce the number of hatchlings come spring.
Other pests, such as ticks, emerald ash borers, and certain agricultural insects, also face winter mortality when temperatures plunge. But again, survival depends on microclimates: a few inches of insulating snow, a south‑facing slope, or a warm pocket under bark can make the difference between life and death.
Why Timing Matters
A sudden cold snap after a mild autumn can be especially damaging to insects. If they haven’t fully hardened off, meaning a physiological process that prepares them for winter, they are more likely to die. Conversely, if the freeze arrives after weeks of steady cooling, many species will already be in their most resilient state.
This year’s freeze, arriving after a stretch of unseasonably warm days in December, may have caught some pests off guard. Egg masses, nymphs, and adults that failed to find proper shelter could experience higher mortality than usual.
The Hope and the Reality
A deep freeze rarely wipes out an entire pest population. Nature is too redundant, too stubborn, too adaptive for that. But winter can knock populations down a notch, buying time for ecosystems, agriculture, and homeowners. Even a 20–40% reduction in surviving eggs or adults can translate into noticeably fewer pests in the spring and summer.
For invasive species like the lanternfly, which have no natural predators here and reproduce explosively, every bit of winter mortality helps. For stink bugs, which have become frustratingly adept at using human structures as winter condos, the effect is more modest but still meaningful.
A Quiet Partnership with Winter
There’s something satisfying about imagining the cold doing some of the work for us. In a world where invasive species often feel unstoppable, winter reminds us that the natural world still has its own checks and balances. The deep freeze may not be a silver bullet, but it is a quiet ally. It is thinning the ranks, slowing the spread, and giving our forests, orchards, and homes a brief reprieve from these damaging insects.
And when spring finally arrives, the survivors will emerge. Hopefully, they will be fewer in number.
References
Brown Marmorated Stink Bug (Halyomorpha halys)
• Cira, T. M., et al. “Cold Tolerance of the Brown Marmorated Stink Bug.” Environmental Entomology, 2016.
• Penn State Extension. “Brown Marmorated Stink Bug: Winter Survival and Cold Tolerance.”
• USDA ARS. “Invasive Stink Bug Winter Mortality Research.” Spotted Lanternfly (Lycorma delicatula)
• Urban, J. M. “Perspective: Shedding Light on the Spotted Lanternfly.” Environmental Entomology, 2020.
• Penn State Extension. “Spotted Lanternfly Egg Mass Survival in Winter.”
• USDA APHIS. “Spotted Lanternfly: Biology and Seasonal Patterns.”
General Insect Cold Tolerance
• Sinclair, B. J., et al. “Insect Cold Tolerance: Ecology, Physiology, and Evolution.” Annual Review of Entomology, 2015.
• Virginia Cooperative Extension. “How Winter Temperatures Affect Insect Populations.”
