How to Kill Hornets in an Attic

Hornets can sting repeatedly to defend their nest.

The hornet provides a beneficial service to the environment by keeping the population of pest insects low. The colony usually keeps to itself, builds its nest away from structures and rarely poses a threat to humans. Occasionally, a hornet colony may take up residence in a home attic or a wall void. The insects pose a danger to people because of their aggressive, protective stinging habits. A homeowner may discover a nest in the attic when he notices the hornets repeatedly flying into a crack in the structure.

Things You'll Need

• Drill
• Powdered insecticide
• Spray insecticide
• Caulk

Instructions

1. Drill a hole into the wall's surface where the hornets enter the attic and nest. Use a drill bit that measures 1/8 inch in diameter.

2. Puff a powdered insecticide that contains bendiocarb, boric acid or chlorpyrifos into the hole. Ensure that the insecticide's label states that it will kill hornets. Follow the powdered insecticide's label for application instructions. Place the tip of the plastic applicator into the drilled hole and puff the powder into the attic.

3. Seal the entrance hole after freezing temperatures have successfully killed any hornets that remain alive in the nest after treatment with the insecticidal powder. Use caulking to create a plug or barrier to the entrance. Sealing the hole will prevent future queens from entering the area and building a new nest.

4. Treat aerial hornet nests located in an attic crawl space or a large attic room using a hornet insecticidal spray labeled for use inside the home. Stand 15 to 20 feet away from the nest. Spray the nest and the nest's entrance hole in a sweeping motion with the insecticidal spray.

Tips & Warnings

• Hornets die during the winter months. Consider waiting until winter for the hornets to die and sealing up the entrance hole to attic to prevent future infestations.

• Spray the hornets nest in the evening when the hornets are not active and have returned to the nest for the night.

• Avoid treating a hornets nest in the fall or the insects may flee the poison and enter the home.

• Never seal a nest hole up until you have determined that all the hornets in the nest have died or they may enter the home when they try to escape.

• Hire a professional pest control company to eliminate the hornets in the attic if you suffer form an allergic reaction to bee stings.

References

• University of Minnesota Extension; Wasp and Bee Control; Jeffrey Hahn, et al.; 2011
• The Ohio State University; Paper Wasps and Hornets; William F. Lyon, et al.
• Washington State University; Yellowjackets and Paper Wasps; Peter J. Landolt, et al. 2003

Resources

• Pest Control Canada: Wasp and Hornet Control