Bees coming and going from a vent inside the home could be an indication that the bees have established a hive in the vent or nearby. Having a bee community inside the home can prove bothersome or even hazardous, especially if someone living there has a bee allergy. As a result, the bees in the vent must be killed and the hive removed to prevent further infestation.
Locate the hive of the bees coming out of the vent. If the vent allows air in from the outside, the bees could simply be coming from an outdoor hive, but if the hive exists within the house, it must be removed to permanently get rid of the bees. Use the flashlight to examine the interior of the vent for any presence of a hive.
Spray the inside of the vent with the bee killing spray, following the directions that came with the spray. Cover the area completely, and make sure the room is well ventilated to prevent excessive fumes.
Seal the vent with the duct tape after spraying it. This will prevent the bees from escaping, and will increase the efficacy of the treatment. Keep the vent sealed overnight.
Remove the duct tape to see if the bees have been killed. If so, put on gloves and remove any hive that is visible. Completely remove all hive components, to prevent bees from returning and rebuilding the hive. If bees are still present and no hive is visible, spray and seal the vent once more.
Unseal the vent after the second treatment if necessary. If bees are still present, the hive may not be located in the vent, but rather somewhere within the house's walls accessible by the vent. In that case, a professional exterminator needs to be consulted, because it may be necessary to remove a portion of the wall to locate the hive and remove it, which is the only way to completely get rid of the bees.