Wasps very often make their nests behind air bricks and these are the very easiest for an amateur to destroy using wasp nest killer powder. Wasps also nest in vents other than sub floor venting air bricks. If in a vent above ground level, be sure to check that the vent does not serve an internal room of the house, or your insecticidal wasp killer powder may enter the internal room when blown into the vent from outside.

Although the wasps are entering the air brick/vent, the nest may be up to 6 feet away under a building or it may be directly behind or to the side of the air brick, ie: in a cavity wall.

Use a powder/dust to kill these wasps. You do not need any application equipment but you may have to make several attempts to eradicate a nest behind an air brick. This is because you cannot get enough wasp killer powder to stay in the entrance path for the wasps to pick up and carry into the wasp nest. Usually, three daily puffs of RENTOKIL WASP NEST KILLER POWDER will do the trick. Apply over the whole air brick as the wasps will use other holes in the brick if you don’t treat all the vent holes. The wasp nest killer powder comes in a small puffer pack, you can also use the POLMINOR DUST BELLOWS to get a more powerful blast of powder into the air brick/vent.

Do it late at night if you are too scared to approach the wasps during the day, however, treatment during the day will be more likely to work rapidly. Even at night, there will be some guard wasps at the entrance to the wasp nest so still take care.
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