1) Wasp nests need to be killed off or they can build up to a dangerous size and over-winter. If you see a few wasps, follow them to see where the nest is. These can be in holes in the ground, in dense vegetation, in holes in walls and, on occasion, in your house roof. It is probably best to call the professionals for any inside your house, but garden nests can be dealt to safely and easily.
2) We use a very small quantity of Lorsban (available to approved handlers only) but any powdered insecticide will work. Carbaryl is widely used. The critical detail is that it needs to be in powder form because you are relying on the wasps unwittingly transferring the powder into the nest. Use gloves whenever handling insecticide as a safety precaution.
3) Mark has a measuring spoon wired to a pole about two metres long. You need a steady hand but this means he never has to get near the nest and he has never been stung using this approach. It takes under half a teaspoon to kill most nests, depending on the accuracy of your placement.
4) Morning is the best time. The wasps are a little dozy because they have not yet warmed up and most are out foraging. As they return they will take the powder in. We do not recommend evening or dusk. You are far more vulnerable to attack when they are all in residence. Move lightly and quietly to sprinkle the poison around the entrance, ideally on the inward side. Heavy footed stomping or noise will put the wasps on alert. It only takes a matter of an hour or two to kill the nest out if you get your placement of the insecticide right.
5) If you want to avoid using insecticide, you can kill them with petrol fumes but you have to get closer and the risk of being stung is higher. Partially fill a small bottle with about 200ml of petrol and plug the top of it into the hole so the fumes and liquid flow in and it blocks the exit. The biggest drawback here is that you need to do this on dusk or at night when all the wasps are in residence. It is the fumes that kill them. Do not set fire to it. Move very quietly and lightly. Generally nests have guard wasps which will fly straight at you. For this reason, Mark strongly favours the insecticide in the morning.