Dealing with Drain Flies: Common Causes & Solutions
Eliminate These Fuzzy Critters from Your Drains
Drain flies—also known as sink flies, sewer gnats, or moth flies—are small, fuzzy insects that often show up in kitchens and bathrooms seemingly out of nowhere. These fuzzy pests typically access your home through your drains, allowing them to easily access your kitchen and bathrooms while their larvae continue to grow deep in your drains. While they’re not harmful in the same way as disease-carrying pests, they can become a serious nuisance if left unchecked.
If you’ve had to deal with these nasty creatures, then you know how annoying it can be to have them flying around your kitchen or bathroom. Let’s take a closer look at where drain flies come from, what attracts them, how they reproduce, and what you can do to eliminate them.
What are Drain Flies?
Drain flies, also known by their scientific name Psychodidae, are tiny insects that typically grow up to about 1/8 inch in length. They resemble tiny moths, with hairy bodies and wings with long furry antennae. Their appearance is one of the reasons they’re also called “moth flies.” Despite their small size, they can be surprisingly persistent and breed rapidly if their preferred environment is available. There are more than 2,600 species of drain flies and they can be found across the world, though most of these species prefer to dwell in wet sludge-based habitats in humid, tropical areas. While Bucks County and the greater Philadelphia area isn’t humid or warm for part of the year, these pesky insects are perfectly content living within drains that mimic their natural habitats.
Where Do Drain Flies Come From?
Drain flies prefer dark, damp, and stagnant environments with a steady food source. This is why they are most commonly found in bathrooms, kitchens, and basements. They are especially attracted to drains that aren’t cleaned regularly, have slow-moving water, or are seldom used. Warm temperatures and humidity speed up their life cycle, which is why infestations often get worse in the summer months.
- Sink and floor drains
- Shower and tub drains
- Toilets that are rarely used
- Sump pump basins
- Septic tanks or sewer lines
- Leaky pipes or standing water in crawlspaces or basements
These flies don’t fly far from their breeding site, so if you notice them in a particular room, the source is likely nearby. Drain flies are also typically nocturnal, appearing at night to seek food sources outside of their slimy homes. They are also naturally drawn toward light sources.
How do drain flies reproduce?
Drain flies thrive on the slimy, organic buildup found inside drains. This slime—also known as biofilm—is composed of decaying hair, soap scum, grease, food particles, and other organic matter. The flies feed on this nutrient-rich film and also lay their eggs in it, making it both their food source and breeding ground. The breeding process of drain flies is rapid and efficient. Here’s how it works:
- Egg Laying: A female drain fly can lay 30 to 100 eggs at a time, typically in the organic buildup within drains.
- Larval Stage: The eggs hatch within 48 hours into larvae, which are about 3–10 mm long. The larvae feed on the same organic material, contributing further to the drain sludge.
- Pupal Stage: After about 9–15 days, the larvae pupate.
- Adult Stage: Within a few days, adult flies emerge and start the cycle over again. The entire life cycle can be completed in less than three weeks.
With the ability to produce so many larvae, it’s no wonder that drain fly infestations can pop up so suddenly – and be so difficult to eliminate!
Problems caused by drain flies
While drain flies aren’t known to transmit diseases to humans, they can still cause problems, especially when infestations grow:
- Nuisance: Swarms of flies around sinks and tubs can be unpleasant and embarrassing.
- Contamination: Their presence around food preparation areas is unsanitary.
- Allergic Reactions: In rare cases, their body parts and excrement can contribute to allergies or asthma symptoms.
- Pipe and Drain Issues: Heavy infestations often indicate underlying plumbing problems, such as sludge buildup or leaks.
How to eliminate drain flies
Getting rid of drain flies involves eliminating both the adult flies and their breeding ground. While it may be tempting to use potent chemical drain cleaners to dispose of them, these chemicals can sometimes have a negative impact on the integrity of your plumbing. Here’s a step-by-step approach to get rid of drain flies safely and effectively:
1. Identify the Source
Place a piece of clear tape (sticky side down) over a suspect drain overnight. If flies appear stuck to the tape the next morning, you’ve found the source.
2. Clean the Drains
Once you have identified the source of the infestation, you’ll want to take action to eliminate the drain flies. Thankfully, there is a relatively inexpensive solution to drain flies – and you likely already have the necessary components in your kitchen cabinet. Pour ½ cup of baking soda followed by 1 cup of vinegar down the drain. Let it sit for at least an hour, then flush with boiling water. Do this as often as necessary until the flies no longer appear.
3. Remove Standing Water
Fix leaky pipes, unclog slow drains, and eliminate standing water in trays, pans, and basement corners. If you’re not comfortable with working on your plumbing, or if you need a drain cleared, give us a call and let our team of plumbers take care of it.
4. Use Traps and Insecticides (if needed)
If adult flies persist, use sticky fly traps near infested areas. In severe cases, a non-toxic aerosol insecticide may help, but focus should remain on removing breeding sites.
Drain Fly Prevention Tips
If you’re concerned about the possibility of a drain fly infestation, here are some steps you can take to prevent these pests from taking up residence in your drains:
- Regular Drain Maintenance: Clean drains weekly with hot water or enzyme treatments. If you need help ensuring that your drains are completely pest-free, call our drain cleaning plumbers in Bucks County!
- Keep Sinks Dry Overnight: Drying out the sink basin and drain can interrupt the breeding cycle.
- Fix Plumbing Leaks: Address any leaks under sinks, behind walls, or near drain traps promptly.
Use Drain Screens: These can catch hair and debris before they go down the drain and contribute to biofilm.
Call McClain Bros. for Professional Drain Cleaning
Drain flies are more than just a minor annoyance—they’re a sign that organic buildup or moisture is present in your plumbing system. By identifying the source, cleaning drains regularly, and maintaining proper plumbing hygiene, you can eliminate an infestation and prevent it from coming back.
If the problem persists or if you suspect deeper plumbing issues, it may be time to call in a professional. Drain flies might be small, but they can point to bigger issues beneath the surface. Our drain cleaners in Bucks County and the greater Philadelphia area are ready to assist you. If you’re experiencing slow drainage, blockages, or backups, be sure to give our team a call. Our plumbers are available 24/7 to assist with your drain clearing needs!
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