What you need to know:
Never spray social wasps that have constructed a nest in a wall void. Sprays tend to flush the wasps into your home. Little by little, you will have wasps in certain rooms. This may continue for up to a month until the nest is exhausted.
Never seal the hole they are using to enter your home. This will have the same effect.
Yellow Jackets getting into your home:
Yellow jackets chew wood/tree bark, wet it down with water or saliva, then use their mandibles to construct the paper they use to make their nest. If they make a nest in a wall void, they sometimes chew the paper and drywall to use as construction material. When they do this, they inadvertently chew through the wall and gain access to the house. If you see what appears to be a stain or wet spot on your ceiling or wall, it could be a Yellow jacket nest about to break through. Very carefully tape over the stained area with painters tape or masking tape. Take special care not to press the soft stained area. You don’t want to push through into a nest of angry wasps. If for instance the spot is eight inches in diameter, you may want to cut out a piece of cardboard one foot square. Tape the edges before you put the cardboard up. Then, gently place the cardboard on the dry wall. You may want to place extra tape over the whole square of cardboard to be extra safe.
Next, you may want to call a pest control company.
In some instances Yellow jackets nesting in a wall void never actually chew through the wall, but somehow are appearing in your home. This usually happens at the end of the season. The queen is the only one that survives. At the end of the season, she leaves the nest to overwinter in another location. When she leaves the nest, the workers will scatter, crawling through wall voids and/or ceiling voids. As they crawl through the walls, they may see light coming from a fixture or recessed lighting. To the wasp, this is the way out. Flying insects are drawn to light. They usually come through an area close to where the nest was. In this situation, you need to tape the suspected areas where you believe they are getting in. If it is recessed lights, take special care to twist the bulbs enough so you don’t accidently turn the lights on with the tape covering the lights possibly causing a fire.
The social wasps can be a nuisance. Social (meaning a queen and her offspring) wasps include paper wasps, yellow jackets, and hornets, all of which will defend their homes vigorously should you disturb them. They have a tendency to build their homes in the places we like to spend our time, so there's a good chance you'll encounter them.
In general, wasps can be distinguished from bees by their lack of body hair and thinner, elongated bodies. Differentiating between paper wasps, hornets, and yellow jackets is a bit trickier. All three are types of Vespid wasps, and share certain physical and behavioral traits: narrow wings that fold longitudinally when at rest; larvae reared on dead or living insect prey; nests constructed of recycled wood fibers; and the ability to sting repeatedly. Paper wasps live in colonies of less than 100 individuals, while both yellow jacket and hornet colonies can number well into the hundreds.
Paper wasps, yellow jackets, and hornets are all masters of papermaking. In spring, the queen constructs a new nest by gathering wood fibers and turning them into a papery pulp, from which she builds a home. Paper wasps build open, umbrella-shaped nests, often found suspended from eaves or window casings on the outside of your home. Hornets are famous for their massive, enclosed nests which can be seen hanging from tree branches or other sturdy structures.
Yellow jackets also make enclosed nests which can be found in the ground (in old animal burrows), in wall voids, attached to a tree branch or on the side of your home.
All the paper wasps, yellow jackets, and hornets produce new colonies each year. Only the mated queens survive the cold winter months, tucked away in sheltered places. The queen emerges in spring, chooses a nest site, and builds a small nest in which she lays the first eggs. Once the first generation of workers matures, these wasps will expand the nest for succeeding generations. In late summer or fall, the old queen dies, and a new one mates before her siblings die off. She leaves the nest and overwinters under a shingle or tree bark etc. The old nest is left empty. Yellow jackets and hornets never re-inhabit an old nest.
Hornets and paper wasps prey on live insects. Their nests are often provisioned with caterpillars to feed their young. Anyone who has enjoyed a meal outdoors in the summer can tell you that yellow jackets like sweets and proteins. Yellow jackets will feed on dead insects, but are just as likely to sip your soda. Of these three types of Vespid wasps, yellow jackets are for certain the greatest nuisance to people.