If you notice a cloud of flies around a plant in your window, don’t confuse it with fruit flies. Chances are they are fungus gnats.

That’s right, even though these annoying tiny flies seem identical to look at, they belong to very different families. So, what are fruit flies? These small brown flies, often referred to as vinegar flies, belonging to the Drosophilidae family. Rotten fruits and alcoholic beverages are their weak spots.

So, what are gnats? There are quite a few species we are talking about here. These come from individual families like Sciaridae, Anisopodidae, and Mycetophilidae. Gnats live on a variety of diets — from vegetables to decomposed materials, even blood. Here’s a fun fact about these insects – they are attracted to sweet, soapy, and perfumy smells? These are some obvious differences between gnats and fruit flies regarding their characteristic nature, habitation, and outlook.

Where do gnats come from? Do fruit flies bite humans? Stay with us till the end to find out such interesting facts.


Difference between gnats and fruit flies


Gnats vs. fruit flies

Through naked eyes, it is difficult to differentiate between fruit flies and gnats in an instant. Both fruit flies and adult gnats are roughly ⅛ inches long. Both are weak fliers and can be hindered by air disturbance. They have slight contrast in body color.

Let’s dive deeper into some of the apparent distinguishing features of these two pest species:


Fruit flies are oval-shaped insects with three body parts: the head, thorax, and abdomen. These flies show many similar attributes to regular large flies. The front part of their body is tan, and the abdomen part is black. The red pair of eyes is a prominent feature of fruit flies. Overall, these flies have a tan or yellowish-brown exterior.

Adult fungus gnats or black flies have comparatively longer, dangling legs, which give them a mosquito-like appearance. They are usually brown or grayish-black in color. Adult gnats have long segmented antennae, which distinguishes them from the short bristled antennae of fruit flies. Eyes are not the best feature of gnats. Unlike the big red eye of fruit flies, gnats’ eyes are merely noticeable.

Life cycle

The complete metamorphosis of Drosophila melanogaster (fruit fly) takes 11-12 days. This length is very much temperature-dependent. Starting from day one with laying eggs, it goes through larva, pupa, and adult form. Adults come out of the pupa on day twelve. This phase is known as Eclosion. Female fruit flies become sexually active only after 8-10 hours of Eclosion. They can produce up to 500 eggs in the first ten days.

Fungus gnats go through the same stages as fruit flies during a life cycle. But it’s a longer cycle, approximately 17 days. The larvae grow into pupae in about ten days, and the adult gnats emerge after four days. Female adults lay almost 100-150 eggs in their short seven day-lifespan. Gnats mature more quickly in a warmer temperature.


As their name suggests, fruit flies are broadly attracted to unrefrigerated and rotten fruits and vegetables. They will fly towards anything smelling like alcohol or containing ethanol. And no, their activities are not restricted only in our kitchen. Fruit flies frequently also thrive in trash cans, clogged pipes, wet mops, and towels.

Gnats are inherently attracted to sunlight, a reason why they are mostly spotted outdoors. Moisty potting soil and decaying organic matters like compost piles are their comfort zones. Although fungus gnats occasionally breed in indoor plant pots, both eye gnats and fungus gnats live outside.

Where do gnats and fruit flies come from?

Doesn’t it seem like the fruit flies came around from nowhere and started a fiesta on your fruit bowl? There was a time when people believed fruit flies were miraculously produced out of rotten fruits. However, the Italian physician Francesco Redi in 1668 and later Louis Pasteur in 1858 disproved the Theory of Spontaneous Generation.

Fruit flies smell fermenting items from far-off places. They look for damp areas and half-ripened fruits to start breeding. And these teensy weensy flies can sneak through the thinnest entrance available. Foodservice and food processing establishments like restaurants, vineyards, wineries face large-scale infestation every now and then. They consider fruit flies to be the most significant nuisance pest.

Gnats, on the other hand, are a severe threat to greenhouses, farms, and nurseries. You can see a gnat infestation at home if the surroundings are moist and humid. The larvae cause root damage to house plants when they feed on the potting soil. Fungus gnats may even breed in damp woods and crawl spaces.

Risks of having gnats and fruit flies at home

Fruit flies don’t bite or sting. Neither are they directly associated with any dangerous disease. But they are highly responsible for food contamination. Fruit flies can transfer bacterias like E.coli, Salmonella, and Listeria from an unhygienic source to other surfaces and fresh food.

Gnats are notorious as biters. Although not all types of these insects bite, some of them could be vicious. Usually, the female black flies and sand flies feed on human blood before laying eggs.
When biting, black flies inject Onchocerca infective larvae into our skin which can cause skin irritation. Some of the typical black fly bite symptoms are itching, fever, burning skin, and blood spots.


No matter whichever one you are dealing with, it’s a critical household hazard. Vinegar traps and duct tape traps are great DIY ideas to check a minor fly infestation at home. You can also get your hands on any commercial traps or insecticide sprays.

However, Bug Guys Pest Control is always eager to come to your service for any professional assistance. Our expert residential and commercial pest control services will ensure that your property is protected with the best preventives. We offer individual treatment and affordable packages. Contact us today to request a free estimate. We will fix a schedule to discuss our prices.