Are Fruit Flies Attracted To Light?


In a recent study performed by researchers at the University of Miami, they found that fruit flies “Drosophila Melanogaster” are attracted to light! But, what’s even more fascinating is that their attraction changes with the time of day!

For example, fruit flies will hover around green light in the morning and late afternoon, but switch over to red light for midday. Interestingly, however, fruit flies were not attracted to blue light as long suspected.

This can be explained by the fact that fruit flies have a much “higher visible light spectrum” than the average fly, allowing them to detect red and green light much more easily than blue.

Fruit Flies Visible Light Spectrum

When it comes to the visible light spectrum, fruit flies react to light in a unique way. In many instances, these bugs are able to detect ultraviolet radiation and polarized light at greater distances than other types of insects.

Scientists have studied bio-inspired approaches to develop innovative photoreceptors from this model organism.

Their research has revealed that the fruit fly’s complex eye structure allows it to perceive a distinct range of wavelengths and intensities from the visible spectrum that most other flies would be unable to see.

In fact, they found that fruit flies can detect light in a much wider range, and can see wavelengths between 300 and 675 nanometers.

Why Do Fruit Flies Avoid Blue Lights?

So we know fruit flies are attracted to certain types of light but, why is it they seem to avoid blue lights? Well, according to Oregon State University, they found that blue lights can actually have negative effects on fruit flies, which can include:

  • Accelerating Aging
  • Retinal Damage
  • Lack Of Energy
  • Brain Neurodegeneration

This was determined by comparing the metabolomic profiles of fruit flies that were kept under constant blue light for 10 to 14 days.

They also discovered that prolonged exposure to blue light caused dramatic changes to the fly’s metabolites, resulting in weak energy production and signs of neurodegeneration.

Fruit flies also suffered damage to their photoreceptor cells, which caused retinal degeneration and accelerating aging involving stress responses.

However, they did note that fruit flies that were kept under blue light for 5 days or less, has no obvious changes which concluded that flies need more exposure to cause any permanent damage.

What About UV Lights?

The short answer is yes! fruit flies are attracted to UV light. In fact, there was a recent study at Harvard University that found fruit flies actually prefer UV light over green light.

This is because flies have a special brain circuit! For example, when insects encounter threats, they experience certain sensations, almost immediately, “an escape reflex” so to speak, bypassing other neural circuits in the brain.

Animals and humans also have something very similar to this, for example, when your startled, you automatically jump, taking over all other sensations in the brain. It’s this same sensation that makes UV light attractive to the fly.

The fly’s photoreceptors also play a role, which is basically special cells in their eye’s retina that convert light into signals! These signals are then sent to the brain which feeds directly into this special circuit making UV light more tempting.

But, UV lights are blue, right? so why are fruit flies attracted to them?

UV light has a short wavelength at 378 nm and is only 40% lethal to the fruit fly. Yet, blue light has a wavelength of 467 nm which is almost 100% lethal if exposed for a prolonged amount of time.

Do Light Traps Work With Fruit Flies?

Yes, light traps do attract fruit flies, but this might not be the best way to eliminate them! Although many people would recommend them as they are relatively easy to use, they tend to attract other insects as well.

Your best bet would be to use homemade fruit fly traps! Not only are they more effective “but” they are also little to no cost to construct.

For example, did you know that fruit flies are actually attracted to vinegar? That right! One type of vinegar impartial that’s great for attracting fruit flies is apple cider vinegar.

Fruit flies are known for being drawn to the smell of fermenting fruit and because apple cider vinegar gives off such a strong aroma the fruit flies are irresistibly drawn to it.

To get started simply pour some apple vinegar into a jar and cover the top with plastic (cleaning film). Poke some holes through the plastic so the fruit flies can get into the jar, once the fly lands on the vinegar, they will get stuck and drown.

Another trap that is very effective for catching fruit flies is sticky traps! Just lay or hang some of these around your house and when they land on the glue they get stuck and die. These traps can be purchased from online stores such as

Lights That Fruit Flies Find Most Attractive

So when it comes to the type of light that fruit flies find most pleasing, we would say green or red light. Although they would prefer UV light over these two lights, you need to remember that UV light is not a natural light source.

Of course, if your thinking about using a UV light for traps then use them! But, as mentioned at the start of this article, studies have shown fruit flies prefer green or red lights above all others depending on the time of day!

If you find that the flies in your home are reacting differently to the light, then you may not have fruit flies at all. Instead, it could be a different species of fly, like the phorids, also known as “humpbacked flies” which look very similar to fruit flies.

Adult fruit flies from the Drosophila genus typically have red eyes with a black, reddish-brown to pale yellow coloration and are 3 to 4 millimeters long with six legs and antennae.

However, there are some fruit flies that are larger than others like the “Tephritidae genus” which are more colorful and typically have black-brown, or yellow, markings on their wings.

Final Thoughts

So, are fruit flies (Gnats) attracted to light? of course! but, as you know now it really depends on the type of light. The bottom line is if your are someone who is trying to remove fruit flies from your home you could try using a UV trap they will work!

However, if you looking for a more natural way that won’t break the bank then try using vinegar for sticky traps! If you find that these methods are not working then again you might not have fruit flies.

If this is the case, and you find that their numbers are increasing you may need to use more drastic measures and call an exterminator.

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