Related Categories

Safety Products

Please be sure to read the product label of any insecticide you choose to use to get information on the personal protective safety gear you will need. In most situations, it is recommended that you wear long pants, a long sleeved shirt, closed toe shoes with socks, chemical resistant gloves, and goggles. In areas where ventilation is poor, a manufacturer may recommend you wear a mask or a respirator. We have put together two different safety kits that will make selecting the correct safety gear easier for you.

Cluster Flies

How To Get Rid of Cluster Flies

The Cluster Fly Treatment Guide

By DoMyOwn staff
Image of a cluster fly

Flies near your windows, doors, and lights in the spring as temperatures begin to warm may be cluster flies. While they are harmless to humans as they do not spread disease, they can be a nuisance, especially in large numbers.

Cluster flies are overwintering, meaning they will try to enter a home or building in the fall as temperatures begin to cool in search of a warm place to survive the winter. Once inside, cluster flies will hide and are usually not seen by people. Instead, they are seen in the spring when the weather warms as they try to leave the building in search of food.

Read this guide to learn how to control a cluster fly infestation. Keep in mind, the best way to control cluster flies is to prevent them from entering your home. Once they are inside, your treatment options are limited. Our guide on how to prevent cluster flies will help you keep cluster flies out of a building.

Step 1

Knock Down Active Cluster Flies

If you have large populations of cluster flies flying around your home or a particular room, you can use a space or contact spray like 565 Plus XLO to knock them down.

Products needed for Step 1


Prepare Room for Treatment

Close all windows, air vents, and doors in the room or rooms you will be treating.


Spray the Room

Image of a man spraying insecticide into a room

Spray the insecticide upward into the open air of the room. Read the instructions on the product for how long to spray. Spray voids where you see cluster flies entering into the room as well.


Leave the Room

Image of man closing a door after spraying insecticide into a room

Leave the room after spraying for at least 15 minutes. Open the doors and windows before re-entering the room.


Remove Cluster Flies

You should see dead cluster flies after spraying. Use a vacuum or broom to remove the dead insects. Be sure to remove the dead insects before treating with a residual insecticide spray and dust.

Space and contact sprays will only kill the flies that are exposed at the time of the application. Hidden cluster flies may emerge later. Read the label of your spray for usage rates and how often the spray can be applied.

Step 2

Treat Your Home with Insecticide

Select a residual insecticide labeled for cluster flies, such as Onslaught.


Mix Your Insecticide

Read the label of your insecticide to determine how much insecticide and how much water is needed. Add half the recommended amount of water to your hand pump sprayer along with the appropriate amount of insecticide. Then, add the rest of the needed water. Replace the top of the hand pump sprayer and shake the sprayer vigorously to mix the water and insecticide together. Remember to wear gloves and long-sleeves while mixing chemicals.

Consult our guide on how to mix and apply liquid insecticides for step-by-step instructions for how to mix and use liquid insecticides.


Spray Inside the Home

Once you have your insecticide mixture prepared, spray the following areas around the inside of your home:

  • Around door and window frames
  • In the corners of rooms where cluster flies have been spotted
  • Where baseboards meet the wall
  • Beneath appliances and sinks
  • Where utility pipes enter the home
Step 3

Dust in Cracks and Crevices

Insecticide dust is a fantastic product to use in hard to spray areas like cracks and crevices. Even better, insecticide dust is long-lasting.


Prepare the Dust

Select an insecticide dust labeled for cluster flies, such as EcoVia WD. Then, fill a bellow hand duster halfway with the dust. Replace the cap of the hand duster and turn the duster upside down, so that the cap is facing the floor. You are now ready to apply the dust around the home.

Products needed for Step 3A


Apply the Dust

Image of a bellows duster dusting into an outlet

Apply 1-2 puffs of dust to the following areas around the home:

  • Where pipes enter the wall
  • Around door and window frames
  • On the underside of lamps
  • In the corners of rooms where cluster flies have been spotted
  • In wall voids behind outlets
  • In cracks and crevices around the home

Do not apply too much dust at once or the dust will not be effective as cluster flies will avoid piles of dust. 1-2 puffs at a time will be plenty.

Step 4

Use a Fly Light

Fly lights plug into standard outlets and can be placed in attics, basements, and rooms that are not often used, like guest bedrooms.

Cluster flies are attracted to the light and then stick to the sticky board (glue board) inside the light. Simply plug in and replace the sticky board as necessary to control your cluster fly infestation.

Pro Tip

If you are short on space, a Gardner Under Counter Fly Light Trap is a smart choice. The Gardner UCT-15 is an easy-to-mount light trap that can be used in hard-to-access locations.

You should see a significant reduction in your cluster fly infestation within a month of treatment. Cluster flies may not be truly eliminated as some may remain hidden, avoiding treatment. If you do not see a reduction, repeat step 1 after 30 days.

Again, the best way to avoid cluster flies is to prevent them from entering your building in the first place. Read our guide on cluster fly prevention to learn how to repel cluster flies away from your home. Click the right arrow below to read more.

877 of 963 people found this article informative and helpful.

Was this article informative and helpful to you?   Yes |  No