Difference Between Fruit Flies and Gnats

Fruit Flies vs Gnats

It is a very commonly prompted question that fruit flies and gnats are or aren’t the same. They are not the same but two different groups of Dipterans. Due to their small size, these dipterans could be easily misidentified. When their morphology and behaviours are considered, it would be easy to distinguish one from the other, and most of the important distinguishing characteristics of both fruit flies and gnats are discussed in this article.

Fruit Flies

Fruit flies are the tiny flying insects that gather around ripening fruits. They belong to the Order: Diptera and there are two main taxonomic families of fruit flies known as Family: Tephritidae and Family: Drosophilidae. Tephritidae flies are larger and more colourful than drosophilae. Additionally, some of the tephritidae fruit flies are pests of agriculture. Drosophila fruit flies are well known for their great significance in studying the basics and some complex theories of genetics.

Fruit flies typically have a brownish head and thorax, usually bright red eyes, distinct black colour patterning on wings, and a dark colour tail or abdomen. The usual size of fruit flies varies around 2 – 4 millimetres from head to tip of the abdomen. They have long and gangly legs and those are visible during flight. Small bristles are present on their head and thorax.

Fruit flies are cosmopolitan in distribution, and that is favoured with their ability to live on rotting fruits and vegetables all over the world. Female fruit flies lay eggs on those rotting surfaces and maximize their population sizes. Despite their significance in scientific studies, economic significance is important to consider; small fruit flies cause more nuisance than direct economic loss to people while larger species (tephritidae) being agricultural pests.


Gnats are the small flying insects in the Suborder: Nematocera of Order: Diptera. The families Mycetophilidae, Anisopodidae, and Sciaridae include the most prominent gnat species. However, there is a common gnat species known as Culex pipiens.

Gnats are very small with about 1 – 2 millimetres long body, which is usually black. Eyes are black in colour, and the abdomen is pointed like an arrow. They have large wings compared to the body size. Gnats have long and gangly legs that look much like mosquito legs; thus, they can jump and fly very rapidly.

Gnats are usually plant sap feeders, but some species are carnivorous. Gnats prefer to gather around warm places, but their usual habitat is water surface. However, some species live on the ground, as well. It is important to notice one of their behaviours that they fly in groups known as ghosts, and those are seen mostly around damp conditions; ghosts fly rapidly in circles. Gnats form swarms of males when they are ready to mate with females. Sometimes these swarms are very aggressive towards each other in competing for females.

What is the difference between Fruit flies and Gnats?

• Although they both are in the same taxonomic order, fruit flies and gnats belong in different families.

• Fruit flies are more colourful than gnats.

• Fruit flies are larger than gnats.

• Male swarms are common among gnats but, not in fruit flies.

• Fruit flies are commonly found around ripening fruits and vegetables, whereas gnats are common in warm places and mostly around water.

• Gnats can bite, but fruit flies cannot.

• Gnats lay eggs on soil while fruit flies lay eggs on rotting vegetables and fruits.