One option for eliminating wasps from a wall starts with identifying their exterior entry point, which provides the location of the wall nest, and setting up a nearby outside trap to lure the wasps out before attacking the nest. Next, dressed in long pants, long sleeves, protective glasses and face covering, seal the point of entry and drill a small hole near the nest. Blow insecticide powder in through the hole, and then cover the hole and repeat as necessary.
Once it is determined that all the wasps are dead, completely remove the nest from the wall, which may require some minor wall repair. It is a good idea to do this at night to reduce the amount of wasp activity.
Some pest removal authorities advise against this approach, noting that attempts to remove wasps from the outside forces them further into the home's walls and woodwork. As well, the use of an insecticide spray in this approach is not recommended. Often, the wasp nest is so far from the entry point that the spray cannot reach the nest. The dead wasps and larva tend to rot when sprays are used, and the moisture from the sprays can result in mold and fungus growth in the wall.
Allergy testing prior to engaging in a wasp elimination project is also advised. Professional pest control is typically the best option for removing wasps from walls.