If you live in Tennessee, it’s common to see insects inside your home during the colder months. Many homeowners are surprised when bugs suddenly appear on windows, ceilings, or light fixtures in the middle of winter. In most cases, these are overwintering pests that moved inside weeks or even months earlier to escape the cold.

The two most common winter invaders we see are Harmonia axyridis, commonly known as the Asian lady beetle, and Halyomorpha halys, known as the brown marmorated stink bug. These insects are not native to Tennessee. Because they cannot tolerate extreme cold temperatures, they look for protected, insulated areas to survive the winter. Unfortunately, homes provide the perfect shelter.

Other overwintering insects

In addition to lady beetles and stink bugs, wasps, mud daubers, and other occasional invaders may also be found inside during winter. Paper wasps and mud daubers often enter structures in the fall while searching for safe overwintering spots. They remain hidden inside wall voids, attics, and other protected spaces during the coldest months. When temperatures begin to warm in late winter or early spring, they become active and start searching for an exit. Instead of finding their way outdoors, they sometimes emerge into living spaces, which is why homeowners suddenly see them indoors after weeks of no activity.

Why & How They Invade Homes

There is no exact date when these insects begin entering homes. As soon as temperatures start to drop in the fall, they sense the seasonal shift and begin searching for warm, sheltered areas. They enter through small openings such as gaps around windows and doors, cracks in siding or brick, attic vents, soffits, utility penetrations, chimneys, gaps around light fixtures, and foundation cracks. Even very small openings can allow large numbers of insects to move inside. The more accessible entry points a home has, the more insects may successfully overwinter within the structure.

What Do They Do During Winter?

Once inside, these pests do not actively infest your home like termites or ants. They do not reproduce indoors during winter. Instead, they hide in wall voids, attics, behind insulation, inside ceilings, behind baseboards, in crawl spaces, and around window and door frames. They enter a dormant state called overwintering and remain mostly inactive until temperatures fluctuate.

Why You See Them During Winter

Homeowners typically notice them on warmer winter days. When sunlight heats exterior walls or indoor temperatures rise, these insects interpret the warmth as a sign that winter may be ending. They emerge from their hiding spots and move toward light sources. Because they are strongly attracted to sunlight and indoor lighting, they are often found around windows, near doors, on light fixtures, and crawling on ceilings and walls in bright rooms. The number of insects you see depends on how well-sealed your home is and how many selected your structure as their overwintering site.

Why Treatment Helps

Professional treatment helps significantly reduce the number of insects that successfully overwinter inside your home. While it is impossible to stop every insect from landing on the exterior, targeted applications around entry points and exterior surfaces create a protective barrier. Treatments are typically most effective when applied in the fall as insects begin seeking overwintering sites. Winter treatments can address current activity if needed, and spring treatments help eliminate remaining insects as they emerge.

What Happens After Treatment?

After treatment, you may still see some insects. This is normal. As they emerge from wall voids and crawl across treated surfaces, the residual product disrupts their nervous system, causing paralysis and death shortly after exposure. Instead of seeing large numbers of live insects, you will primarily notice dead ones. Treated interior surfaces provide residual protection for several months, while exterior treatments generally last about 30 days, depending on weather conditions.

It is important to understand that pest control focuses on control and reduction, not absolute prevention of every single insect. Some activity on warm winter days can still occur, especially if insects were already inside before treatment.