How to Keep Stink Bugs Out of Air Conditioners

Rena Sherwood

The brown marmorated stink bug (BMSB) hibernates during the winter. Stink bugs invade homes in the autumn looking for hibernations spots, such as window air conditioners. The BMSB produces a horrible odor when threatened, which makes them a nuisance in the home.

Stink bugs can hibernate in air conditioners.

To keep stink bugs out of air conditioners, the homeowner needs to initiate a multi-faceted prevention program. Stink bugs can enter homes through any small opening and not just through the air conditioner.


Stink bugs do not get into central air conditioning power units since they are outside the home. If living in an area where stink bugs are a constant problem, switch from window air conditioners to central air conditioning as soon as possible. For those with central air conditioning, check vents and tubes that connect from the unit into the home. Fill in any gaps with caulking. Cover any open vents with 20 or finer wire mesh.


Never spray insecticides on an air conditioner, especially if the air conditioner is turned on. Insecticides are flammable. They will not prevent stink bugs from getting in the house and are not good as a long-term solution.

  1. Place fiberglass shade-blocking screens on the outside glass of windows holding air conditioners. They may be sold as “solar shade window screens” but they will also block insects from coming through that part of the window, according to the South Carolina Energy Office.

  2. Remove small air conditioners from windows at the end of August. Stink bugs enter the home through the air conditioner. Stink bugs can use the air conditioner itself as a hibernation place but may also move through the air conditioner into other areas of the home. If the air conditioner is too big to move, go to Step 3.

  3. Place weather stripping around windows, doors and air conditioners that are too large to remove. Stripping seals off narrow cracks that stink bugs can crawl through.

  4. Repair or cover any holes in window screens. To keep bugs out, the mesh diameter should be 20 or finer.

  5. Fit the entire outside portion of a window air conditioner with a commercially made air conditioner cover. These covers may be sold as water-blocking covers. The air conditioner cannot be run with a cover on.