All About Drain Flies

Drain flies, sometimes called moth flies are non-biting gnats with dark wings. Drain flies can be a nuisance for home owners. In this article we discuss how to identify and treat a drain fly problem.

They can often be found resting on ceilings or walls, and take sort of “hopping” like flights if disturbed. Often drain flies are a temporary problem, since they develop in standing water. For instance, if you are gone for vacation, you may return to find drain flies, but once your household normal activity is renewed, the drain flies usually go away. If you notice that they are a problem over several weeks, you more than likely have a breeding site somewhere that should be located and cleaned to eliminate the drain fly.

Sources of Drain Flies

If you have flies in your home or workplace, identifying the breeding ground and its treatment is the key to controlling small flies.
The larval drain flies need moisture to survive and they can bread anywhere that water is standing for a week or so. Infrequently used toilet bowls and tanks, sink or floor drains in basements or garages, or drain pans under refrigerators.

Drains can present one of the most overlooked sources for breeding of small drain flies. Drains can look clean on the surface but pose an enormous breeding ground underneath. Floor drains can create an organically rich environment that will attract and breed insect growth.

Drains that have failed, have cracked or damaged pipes can be a major culprit in you insect problem. You may even be able to see the gray wriggling larvae swimming in the water.

All of these areas need to be cleaned thoroughly and be sure to remove surface film in order to kill drain flies and keep them out.

Drain fly larvae can remain submerged for a day or more because they are able to trap air bubbles, so they are very difficult to drown. The drain fly life cycle takes from about 10 to 15 days at about 70° F. If drain flies disappear and reemerge after 10-15 days, you know you will need to retreat your drains.

Here are a few recommendations for keeping your drains insect free:

•Pouring hot water down the drain may provide short-term control.
•Clean your drains regularly-drains should be opened and cleaned on a regular basis, using a wire bristle brush will help remove any excess organic matter.
•Check drain traps and remove any debris that may end up clogging your line.
•After cleaning drains use of a drain cleaner or biological agent into the drain is advised. As with all products follow label recommendations for use.

Although they are non- biting, drain flies and their larvae are just unsightly and annoying. Follow the prescribed measures and drain flies should be a thing of the past!

Monica Bird (933 Posts)

Monica’s compassion for her customer's struggles with pest control issues and passion for pest control stems from over 10 years in the industry. With a master’s degree in entomology, she uses her knowledge and experience in chemistry, insects and pests to educate her customers.


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