House Flies

Combat Negative Air Pressure and Flying Insect Infestations

As we approach warmer days for spring and summer, flying insect activity(flies, mosquitoes, wasps, moths, stored product insects, etc.) will become a serious threat inside commercial buildings with negative air pressure.

What is negative air pressure? As you exit your building, do you get that push of air meeting you? This is negative air pressure. Scientifically speaking, it occurs when the pressure inside your facility is lower than the pressure on the exterior.

Why is this bad?

  • It increases the amount of flying insects being sucked into your building.
  • Higher energy bills.
  • Poor indoor air quality.


Simple steps to take against negative air pressure and decreasing the amount of flying insects inside your facility.

  1. Call an HVAC specialist. It could be as simple as repairing duct work or adjusting fan motors.
  2. Keep exterior doors and windows closed as much as possible. Have employees exit for breaks, etc. at the customer entrance or at one exit point.
  3. If you have a compactor door that opens on the interior of the building, make sure it remains closed when not in use and is properly sealed to prevent pest entry.
  4. Make sure your dumpster or compactor is cleaned and rotated regularly to prevent breeding sites and attractants for flies.
  5. Keep the exterior area around and under the dumpster cleaned.
  6. Move garbage cans away from entrance doors and have them cleaned to prevent attracting insects to entry points.
  7. Contact your pest provider and have fly bait stations installed at the dumpster area to reduce fly activity.
  8. Speak with your pest provider about residual pesticide applications to landing and resting surfaces for flies on the exterior of the facility.
  9. Ensure door sweeps are installed and undamaged at doors, dock doors, and dock plates. An astragal should be installed and undamaged on double doors.
  10. Isolate areas within the facility by keeping interior doors closed. If you can isolate areas of high insect entry, it will reduce activity in other areas of the facility.
  11. Power down lights when not in use. These will attract insects to the building at night.
  12. Remove lighting near doorways and add a light directed to the doors some distance away from the building. This will attract insects away from the entry points, but still provide lighting for entry of staff and customers.
  13. Installation of insect lights in areas to intercept insects before proceeding further. Insect lights should not be mounted in areas that can be seen from the exterior. Insect lights are attractants and will draw insects to the building and create additional problems. Contact your pest provider for additional assistance.
  14. If your pest provider does not currently maintain insect counts on your insect lights for type of insect and numbers, request them to begin. This allows the pest provider as well as you to see the areas of the building generating the highest counts and species of insects. Once this data is found, it allows additional focus on these areas to obtain an overall decrease in the number of flying insects inside the facility.
  15. Remove standing water around the perimeter of the facility to prevent attracting insects to the building.
  16. Install air curtains above frequently used doors, dock doors, and interior compactor doors. If you currently have an air curtain over the doors, check the following:
  • The air curtain should extend slightly over each end of the doorway.
  • The air curtain nozzle should be adjustable and aimed at 20 degrees outward from the opening.
  • Check the airflow to ensure it covers the opening to the floor.
  • Air curtains should be cleaned every 3 months or more often in dirtier environments.
  1.  Below are steps to clean your air curtain: Switch the power off at the service panel and lock the service panel to prevent power from accidentally being restored.
  • Remove the air intake grille for access to the blower housings and motors.
  • Vacuum and clean to remove the buildup of dirt and debris.


If you have any additional questions, Epituer Pest Solutions, LLC can be reached at 865-363-1155 or click here.

Epituer Pest Solutions, LLC services Knoxville, Tennessee, and surrounding areas of East Tennessee.


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