How to get rid of drain flies in restaurants

Quick overview

• Drain flies breed in the organic slime coating the inside of drains.
• Restaurants are high-risk due to floor drains, grease traps, and constant food waste.
• Standard cleaning products won't remove the biofilm that drain flies need to breed.
• Missing even one breeding site means populations can rebound quickly.
• Recurring drain fly activity may indicate the need for a professional inspection and treatment plan.

Spotting small flies in your restaurant is a problem that needs attention. Drain flies are among the most common fly control issues in food service environments, hovering near floor drains, mop sinks, and the bar. While they may seem minor, their presence can signal a hygiene issue. This guide covers what drain flies are, why restaurants attract them, and the most effective steps to help get rid of them.

What are drain flies?

Drain flies are tiny, moth-like insects, around one-eighth of an inch long, with fuzzy wings that give them a dusty appearance. You might also hear them called moth flies or grease flies, since they breed in the grease and organic buildup inside commercial drains. They're weak fliers and tend to rest on walls near their breeding sites rather than moving around the room.

They're sometimes confused with fruit flies, which are smaller, more active, and drawn to overripe produce and sugary liquids. Our fruit fly pest guide can help you tell them apart.

How to get rid of drain flies in your restaurant

Learn how to get rid of these little flies with tips from our fly control experts.

1. Clean and treat your drains

The most important step is removing the organic film that drain flies breed in. Scrubbing the inside of drain pipes with a stiff brush helps break up the buildup that standard cleaning products can't reach. Once you’ve scrubbed the inside of the drain, use a drain treatment product designed to break down organic matter.

Remember: you need to go beyond pouring drain cleaner down the drain, as the gelatinous film coating the pipe walls needs to be physically removed. Regular deep cleaning of all floor drains, including those in low-traffic areas, should be part of your kitchen maintenance schedule. Our biological drain-cleaning service uses microorganisms break down organic waste in drains.

2. Eliminate all breeding sites

Cleaning the drains is essential, but it’s not the complete approach. Drain flies can breed in any area of standing moisture and organic waste, so a thorough approach covers the following areas.

• Emptying and cleaning grease traps on a regular schedule
• Removing standing water from under equipment
• Replacing or thoroughly cleaning wet mops and mop buckets
• Checking for leaks under sinks and around pipe fittings
• Keeping waste bins sealed and emptied frequently

3. Use traps and monitoring tools

Insect light traps are a practical tool for capturing adult flies and monitoring activity levels in your kitchen. They won't solve the root problem on their own, but they help reduce adult populations while you address the breeding sites. They also give you a clearer picture of where activity is highest.

How Presto-X can help get rid of drain flies

DIY cleaning and trapping can reduce numbers in the short term, but drain flies reproduce quickly. If any breeding sites are missed, populations can quickly bounce back. 

Our technicians inspect every potential breeding site, including floor drains, grease traps, and utility areas, and build a tailored treatment plan using an integrated pest management (IPM) approach. And as part of our commercial pest control services, we provide documentation to support audit requirements.