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Sump Pump Guide The Ultimate Guide to Sump Pumps

How To Get Rid Of Drain Flies In Sump Pump Pit

Drain flies are annoying pests that live in sump pits and other low-lying areas. They breed rapidly and lay eggs in moist soil or water. The larvae hatch from the eggs and feed on decaying organic matter.

Drain flies are attracted to moisture and food sources. If they are present in large numbers, they can cause serious problems such as clogged drains, blocked sewer lines, and even sewage backflow into homes.

Sump pumps are designed to remove water from basements, crawl spaces, and other areas where it collects. However, if drain flies are present, they will find their way into the pump pit and make a home there.

The best way to get rid of drain flies is to prevent them from entering your sump pit in the first place. This means keeping the area around the sump pump free of debris and other items that could attract insects. It also means cleaning out the sump pit regularly so that you don’t have any standing water for the flies to use as breeding grounds.

sump pump pit

If you do discover drain flies in your sump pit, try these tips:

  • Use an insecticide spray to kill adult flies. Don’t worry about harming beneficial insects like ladybugs and spiders; they won’t be affected by this treatment.
  • Clean up the area around the sump system with a stiff brush. Remove all leaves and other debris that might hold water.
  • Clean out the sump pit at least once every week using a garden hose or similar device. Make sure that the water runs clear before allowing it to flow through the sump pump.
  • Keep the area around the sumps clean and dry. For example, keep grass mowed short and rake away leaves and debris.
  • Check your sump pump frequently for signs of wear and tear. Replace worn parts promptly.
  • Install screens over the openings at the bottom of the sump pit. These help keep small animals and insects out while letting air circulate freely.
  • Seal cracks and holes in the walls of the sump pit with caulk.
  • Cover the opening at the top of the sump pit when not in use. Doing so prevents rainwater from seeping into the pit and attracting more mosquitoes and other insects.
  • When possible, install a roof over the sump pit. Roofs help protect against heavy rains and snowmelt.
  • Consider installing a dehumidifier in the basement to reduce humidity levels.

Finally, consider adding a trap to the sump pit. A simple box filled with soapy water works well. Place it near the intake pipe leading into the sump pump. You may need to check periodically to ensure that the trap doesn’t become too full.

How to Find Out Where They Come From?

If you suspect drain flies may be causing problems, check to see if they are present near your sump pump. If not, then you know that they must be coming from somewhere else.

You can determine this by looking at the drainage system in your basement. Check for holes or cracks in the flooring. These are likely to lead to the outside.

You can also look for signs of water damage. Water stains on walls or ceilings are an indication that water has been leaking through the roof or exterior wall.

Also, look for small openings in the foundation. These can allow insects to enter the house.

What Can I Do About Them?

There are several ways to keep drain flies away from your sump pump pit.

First, try to keep the area around the pump clean. Remove all debris, including leaves, grass clippings, and other things that might provide shelter for insects.

Next, consider installing a screen over the opening of the sump pit. Screen mesh should be no larger than 1/4 inch thick. You can buy these screens at most hardware stores.

Finally, install a lid over the top of the sump pit when it isn’t being used. This will help keep the area dry and insect-free.

How to Kill Them?

Once drain flies have made themselves at home in your sump pit, there is only one sure way to kill them: heat!

Heat kills many types of insects, including drain flies. A simple method involves placing some hot rocks in the bottom of the pit. As the stones warm up, they release steam which creates enough pressure inside the pit to force the fly larvae out of the ground.

A more sophisticated technique uses propane torches. These devices produce high temperatures that are ideal for killing drain flies.

How to Prevent Their Return?

To ensure that drain flies do not return to your sump pit, seal off the opening with a piece of plywood or plastic sheeting. Make sure the material is sealed tightly against the sides of the pit.

This will prevent the insects from escaping once they are dead. Once the trap is set up, you can periodically check it to make sure that nothing has crawled through the hole.

Another option is to cover the pit with a tarpaulin. This will help protect the area from rainwater and snow melt.

How to Get rid of them Permanently?

Insects such as drain flies are attracted to decaying organic matter. Therefore, you need to remove all rotting vegetation and other materials from the area where the sump pit is located.

The easiest way to accomplish this is to hire a professional landscaper to come in and take care of the job.

If you don’t want to pay someone to do the work, you can use a garden hose to spray down the area. Be careful not to get any water into the pit itself.

If you decide to tackle the job yourself, you will need a strong vacuum cleaner. The best type of vacuum for this purpose is a shop vac. Use the nozzle attachment to suck up all the debris. Then, run the machine backwards to lift the dirt out of the pit.

sump pump cover

You may find that removing the soil from the area takes longer than you expected. If so, just stop every now and then to let the vacuum rest.

When you finish cleaning up the area, apply some insecticide to the spot. Insecticides are available at most hardware stores. They are usually sold in aerosol cans.

When using an aerosol product, follow the instructions on the label carefully. Don’t spray directly onto the ground because you could harm plants or animals.

Instead, spray the insecticide into the air. Wait until it settles before spraying again.

After applying the insecticide, wait several days before checking to see if the problem has been solved. If you still notice drain flies after waiting this long, repeat the process.


Drain flies are annoying pests that can cause significant damage to your property. Fortunately, there are ways to deal with their presence.

Fortunately, these pesky insects can be eliminated easily by following the steps outlined above. You should be able to eliminate these pests without having to spend too much time and money doing it.

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