Hello Elisabeth,

Can you share a photo of the wasps being found? If we can identify them, we can provide more specific information.

In general, though, social wasps (yellowjackets, paper wasps, and hornets) all die each winter and nests are not re-used from one year to the next. Only young queens (mated females) that were born late last summer will survive, having left the nest and overwintered in a hibernation-like state in a sheltered spot on by themselves.

In spring as the weather warms, she will "wake up" and explore the landscape for a potential nest site. She does all the work of starting a new paper nest structure and raising the first generation of daughter wasps by herself, so it can be hard to tell where a new nest is since there will be very little activity to see with only one wasp working on it. Later in spring, when those daughter wasps are mature, they will take over nest-building and sibling-rearing duties and the queen stays in the nest for the rest of her life. As the colony's population gets larger into the summer, the workers busily coming and going might reveal the location of a nest. Even so, they tend not to bother people unless directly threatened by attempts to remove a nest or swat the workers. Treatment with wasp spray is not usually needed if the nest can be avoided, and it will die out sometime in autumn.

It's not unusual for wasp queens to overwinter indoors if they find an access point like a gap/crack in an exterior wall, worn-out door weather-stripping, or even an open window with torn insect screening. They come inside only to seek warmth and shelter, and in their attempts to leave in spring, get confused by light sources since, to insects, a source of light is usually the sky and therefore a means to escape a dark enclosed space. They should not sting anyone unless defending themselves from being caught or swatted. If they die as they wander the house trying to leave, they likely ran out of energy (body fat, since they can't find food like flower nectar or tree sap to drink) or dehydrated.

Since wasp queens will not have reached the point of having a colony of workers this early in the season, finding multiple wasps inside simply implies that several queens (which might have grown up in a nest nearby last year) found the same appealing cozy spot to explore; it is highly unlikely to indicate an active nest already in the building. Therefore, individuals can be ushered outside as found, or just removed if they die in the process.

Since their presence demonstrates that they found a way inside in the first place, though, it might be worth investigating possible routes of entry that can be better sealed before a new queen does find a spot to set up camp inside a wall. Yellowjackets are the smallest of the social wasps, and can use fairly small gaps in exterior wall junctions, loose or damaged siding, roof soffits, vent covers, and degraded sealant around pipes/cables entering the house.

Miri