What Do Gnats Eat? 5+ Foods In Their Diet

Written by Volia Nikaci
Published: December 29, 2021
Image Credit iStock.com/Tomasz Klejdysz
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Have you ever wondered what the small flying insects buzzing around your face are? Gnats, sometimes known as no-see-ums, are tiny flies that belong to the Mycetophilidae family, a family of small flies.

Ranging from gray to black in color, these tiny insects sport long legs and strong antennae. They’re so small, that adult gnats are often mistaken for baby flies, even though they are actually fully grown. 

Usually found in large groups, gnats can be identified in the swarms they hang out in at night. Only growing to about 2.5 millimeters long, it may be hard to believe that these tiny insects can even find anything to eat.

We’ll explore the gnat’s favorite foods and discover the surprising differences between the gnat species. 

What Do Gnats Eat?

What Do Gnats Eat

A-Z-Animals.com

Gnats eat a variety of fruits, vegetables, and decomposed plant matter for most of their diet. Gnats are predominately herbivores, however, some are classified as omnivores.

The majority of gnat species eat soft, sweet fruits and as a result, are often confused for fruit flies. Fruits are an excellent source of food for both adult and larval gnats and they enjoy laying their eggs inside them. 

Here is a list of the most common foods gnats eat: 

  • Overripe fruit 
  • Algae 
  • Softening potatoes 
  • Compost 
  • Fungus 
  • Decaying organic matter 

Gnats also appreciate a wide range of veggies and will lay their eggs inside soft-shelled or decaying plants. The decomposing plant matter is another favorite as they love to eat and often thrive in damp areas. 

They aren’t particularly picky eaters either and you can also find them enjoying slime that forms on water or wet soil as well as moist manure, animal carcasses, and plant roots. 

What Do Different Types of Gnats Eat?

Dark-winged fungus gnat, Sciaridae on a plant. These are common pests of ornamental potted plants in homes.
Gnats are common pests of ornamental potted plants in homes.

iStock.com/Tomasz Klejdysz

Since there are so many distinct types of gnats, they all eat different things. Some gnats are biting insects, while others are not. Adult gnats’ mouths are classified as one of three types: lapping, sucking, or piercing. 

The term “gnat” is more a descriptive term (similar to bugs) rather than being scientific. As such, the definition of which flies are called gnats can change.

Gnats, both male and female, feed on plant nectar. However, females in some species also require blood in order to lay eggs. When a female gnat bites the skin, she does so with the scissor-like mouth structures that allow her to pierce through the skin. 

The different types of gnats include: 

  • Fungus Gnats
  • Eye gnats
  • Sandflies
  • Buffalo gnats or black flies
  • Phorid Flies
  • Drain Flies
  • Midges

The small biting bugs include the midges, sandflies, and no-see-ums. Interestingly enough, gnats may either feed on hosts individually or in swarms. 

What Do Baby Gnats Eat?

Baby gnats are called larvae. They hatch from eggs and become larvae that resemble small worms, and then go through a pupae stage before becoming gnats. 

Not all gnat larvae eat. Interestingly enough, some such as the fungus gnat larvae, simply survive until they reach the pupae stage. At this point, they will begin to eat as adult insects.

For the gnat larvae that they do, they will feed on the environment in which they are born. If the larvae were hatched in fruits or vegetables, then they will begin to eat these until they are ready to emerge. 

The same goes for gnats that hatch in soil as they will begin to eat degraded plant materials, fungus, and plant roots.

Are Gnats Dangerous To Humans?

Gnats can bite people in some cases. The bites typically result in small, red lumps that are uncomfortable, itchy, and annoying. While it is unusual, gnat bites can trigger serious allergic reactions in certain people.


While serious reactions to bites are uncommon, you can become sick if they contaminate foods with their waste or if you ingest fruits with larvae. Another major downside to gnats is that they help the spread of pink eye in humans. 

If you happen to get bitten by a gnat, there are a few simple steps that you can step to relieve the symptoms such as gently washing the area with soap and water, applying a cold compress, and using anti-itch creams. 

How Much Do Gnats Eat?

Fly Lifespan - Gnat
Gnats fly in clouds that can cause destruction to crops.

Henrik Larsson/Shutterstock.com

Gnats are small insects individually, but because they prefer to fly in clouds, they may do significant harm to crops and plants. While a single gnat might not do much damage in terms of how much one can eat, an entire swarm can easily become destructive. 

A gnat cloud may easily destroy all of the fruits on your fruit trees and can be disastrous for fruit farms. Larvae that are feeding can also cause serious damage to plants and prevent them from growing. 

How Does The Gnat Diet Impact Other Species?

While we may find them to be a pest, gnats do serve an important role in nature. Their eating habits can help in the breakdown of certain materials and they also aid in the regulation of plant populations by delivering nutrients from one plant to the next. 

When they’re not helping to pollinate flowers, they make for a tasty snack for birds, bats, and other bigger insects. In fact, they serve as a particularly important part of aquatic food chains.

Although annoying, if gnats were to suddenly disappear off the face of the earth there would be serious implications to the rest of the ecosystem

While this doesn’t mean that you have to let a gnat infestation take over your home, it does serve as a reminder of the importance of even the smallest animals in the earth’s ecosystem. 

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About the Author

Volia Nikaci is a copywriter and content editor with a passion and expertise in SEO content creation, branding, and marketing. She has a background in Broadcast Journalism & Political Science from CUNY Brooklyn College.