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Fruit Flies, Drain Flies, and Gnats–Oh, My!

With how often meals are prepared and how social mealtimes can be, the kitchen is one of the most important rooms in the house. But we aren’t the only ones who like to hang out there. Between fruit bowls, houseplants, and drains, kitchens are a hotspot for various flies and gnats. But which one is bugging you? Let’s look more closely at the differences between gnats, drain flies, and fruit flies so you can better understand what you are dealing with. While none of these insects bite or sting, we know the nuisance they can cause and will go over them, as well as some treatment methods below.

Fungus gnat” by andybadger is licensed under CC BY-SA 2.0


Gnats, also called no-see-ums, are frequently confused with other insects. Like all insects, they have 3 body segments, 6 legs, and 1 to 2 pairs of wings. They are usually less than ¼” long and can be dark brown, tan, or yellowish in color. There are many types of gnats: fungus gnats, eye gnats, sand flies, buffalo gnats, fruit flies, phorid flies, drain flies, and midges. That’s right–fruit flies and drain flies are both types of gnats! 

Gnats have three types of mouthpieces: lapping, sucking, and piercing. They use these to feed on decaying organic material. What they eat specifically depends on the type of gnat. For example, fruit flies eat overripe fruit, fungus gnats eat fungus, and drain flies eat drain buildup. Though each gnat only lives about one month in total, females lay up to 300 eggs in their 10-day adult lives. Since they reproduce so speedily, a few gnats can quickly turn into an infestation.

Gnats are moisture bugs, so infestations are usually in damp areas. Garbage heaps are gnat paradise, as the smell attracts them and conditions are ripe for breeding. Food left on the counter also emits odors as it begins to decay. Houseplants can attract gnats as well. The excess water in the soil will act as a gnat beacon. And even if the surfaces you can see look pristine, don’t forget your drains! As homes age, pipes accumulate built-up organic material that gnats love to eat. The best thing to do if you find yourself with gnats in your home is to clean in order to remove the decomposing material that is attracting them. Another tip is to try to figure out how they are getting into your home and work to eliminate possible entry points.

Fruit fly” by John Tann is licensed under CC BY 2.0

Fruit Flies

Though they are a species of gnat, fruit flies have several distinct differences. First, they are much better fliers than gnats. Most gnats are known for being weak fliers, but fruit flies are very different. They beat their wings 220 times per second and can turn in midair within one one-hundredth of a second.

Also, their senses are more heightened. Fruit flies have over 700 lenses on their eyes and ⅔ of their brain is devoted to visual processing. Their visual field is around 270 degrees, and combined with their flying skills this means they are very good at evasive maneuvers. And it isn’t only their vision that is remarkable–their antennae can also sense the chemicals secreted by rotting fruit from up to a mile away. 

Third, they have a very fast reproductive cycle. Their full life cycle is closer to 2 months–about twice the length of most gnats–and by day 11 or 12 they are able to breed on their own. Females can lay 100 eggs per day which hatch in less than 24 hours, and in under 2 weeks that generation will already be reproducing. This is great for scientists who use them to study genetics, but terrible for homeowners who find themselves overrun by fruit flies! Fruit flies lay their eggs in rotting fruit or vegetables, but their larvae also feed on organic material found in drains, so both areas should be cleaned if you find yourself overrun by fruit flies.

Drain Flies

Though these are also a species of gnat, they are sometimes called moth flies because they are fuzzy and look like small moths. They are also usually more active at night. Adult drain flies live for 20 days and breed once, with the eggs hatching within 48 hours. Unlike fruit flies and gnats, drain flies are usually a temporary problem uncovered after returning to the home having been gone over a week, because they develop in standing water. Often, getting the water running regularly again is enough to reduce the population sufficiently. 

But if you are seeing these brown fuzzy creatures week after week, there may be a breeding site nearby. As they are also moisture bugs, any drain in any room can be enough to attract these slow-flying fuzzy insects. Thorough cleaning of pipes and traps is key to eliminating drain flies, but since the larva can live over a day submerged in the water this can be a difficult task. 

Stay Informed And Protected With Spidexx

When you are dealing with small annoying flying insects inside your home, knowing what you are up against is half the battle. Armed with the similarities and differences between fruit flies, gnats, and drain flies, we hope you have learned some ways to differentiate between them and better identify what’s happening inside your home, as well as some helpful ways to mitigate them. While thorough cleaning is the best eradication for fruit flies and gnats, Spidexx does offer a drain fly treatment to help keep your home drain-fly free!

Call our office at (844) 922-7732 or get a quote online.