Why Flies are Drawn to Light Sources | Dr. Killigan’s


Why Are Flies Attracted to Light?

It is the most curious thing. Temperatures rise, and insects start to make their appearance. Mosquitoes buzz around your porch, upsetting your outdoor activities. Bees and wasps chase your kids indoors, and flies make their trip indoors to make your life miserable. They fly around from room to room, they watch you cook a meal, then for some reason they all disappear. Where did they all scamper off to? You begin to look, and you find them, all gathered around one place, the brightly lit windowsill. But why? Why are flies attracted to light?

The Fly is an Interesting Insect

We see them every day and we rarely give them a second thought. But flies are really a unique creature. Here are some quick facts about flies.

  • Flies only have two wings. While most other insects have four. The house fly only has two.
  • Flies only live about a month. After a fly has matured, they do not live long. Generally, one to two months.
  • Flies are pretty disgusting. The life of a fly is continued through decaying matter. This is where they lay their eggs.
  • Flies live on a liquid diet. They don’t even have teeth. They go through a process of liquifying their food and slurping it up through a mouthpart called a proboscis.
  • Flies are daytime insects. You will not likely see them flying around at night time. They are highly reactive to light. This is primarily due to the makeup of their eyes.

The Eye of the Fly

The eyes of the fly are unique. Within each eye there are thousands of photoreceptors, called ommatidia, which are specialized cells found in the retina. Each of these receptors converges to create a picture for the fly to see. However, this picture is not as clear as you or I see, it is much like a mosaic, thousands of tiny pictures making one larger picture. You would think with so many eyes that they would have fantastic vision, but they do have their limitations, but their vision does give them some benefits.

  • Limitation: Their eyes cannot focus. – Our eyes see shapes, colors, and motions. We can interact and react to their changes based upon how they interact with us. We see an object we can determine what it is and whether or not it poses a threat. Flies, on the other hand, do not have the ability to focus; they only see motion. So, any movement is perceived as a threat, and they react based on that notion.
  • Benefit: Their eyes enable them to be fast. – Those thousands of receptors function as individual eyes. This gives them a keen sense of motion. While they cannot fully make out what they are seeing, they can see what is coming to them, and they are lightning fast with their reaction. You most likely notice how fast they are, with how difficult it is to swat them.
  • Benefit: Their eyes allow a 360˚ view. – This is why you cannot sneak up on a fly. Their eyes are bulging and convex. With this raised point of view, they can see in front, behind, and to each side.
  • Benefit: Their eyes see light in different spectrums. There are lower levels in the UV spectrum that human eyes cannot see. But the way that a fly’s eye is designed, they can see these spectrums. It is all very scientific and filled with fancy jargon, but their ability to see these low levels aids in their ability to see and react in ways that humans cannot. In fact, studies have shown that flowers and other plant life emit this spectrum, and pollinators like bees and flies are attracted to them to aid in cross-pollination. This spectrum is also why they are attracted to UV light bug traps.

Flies and Their Interaction with Light

There is actually an entire study on how flies interact with light. It is a derivative of the term ‘taxis,’ which is the directional movement of something based upon stimuli. In this case: Phototaxis – the movement of insects toward or away from light sources. There are two types of taxis, a negative reaction and a positive reaction.

  • Negative Taxis – This directional movement is away from a light source. Flies generally do not have much of a negative reaction to light. Instead, they are drawn to it.
  • Positive Taxis – The preference to move toward a light source when presented with it.  With flies, it is not necessarily the light itself, but the UV rays the light source is casting. You have heard the old adage, “like flies to stink,” well, it should be more like, “like flies to UV rays.”

Ultraviolet light, UV for short, are light rays that are outside the color spectrum of human vision. The natural color spectrum consists of seven colors: red, orange, yellow, green, blue, indigo, and violet. All the colors we see lay somewhere in between red and violet. If you go outside that defined parameter, beyond violet, you are now into the ultraviolet scale.

UV is more than just a color; it is a wavelength. This is why it is often paired with the term ‘rays.’ UV light rays have other properties associated with it. One is that it is the wavelength that is responsible for your summertime sunburn, as well as the infamous hole in the ozone layer. But UV rays are also part of the beautiful handiwork of giving springtime flowers their beauty. And as we mentioned earlier, the attractiveness to flies, bees, and other cross-pollinators to spread and continue the process.

Positive Taxis, UV Rays, and Your Home

Positive Taxis is why flies are most active during the daytime and are out of sight when the sun goes down. When they lose their light source, flies are pretty much helpless. As we have learned, they cannot focus because of their compound eye; this makes them completely light-dependent. So, when the sun rises and they begin seeking places to soak in that light source again, the first place they will turn to, especially when they are locked inside your home, will be an access point to the outside world: a windowsill.

 Flies are inborn with positive taxis. They seek out light sources, especially UV light rays. Their eyes are designed specifically to find this source. Light bulbs do attract flies as do other light sources. When those artificial lighting sources emit UV rays, like black lights, they are especially drawn to it. These are the lights used in pest control devices like bug zappers. They are meant to attract flies, moths, and other flying insects, and through other means, dispose of the insect.

There are other ways to use natural UV light rays, and the natural instinct of flies, to dispose of them when they become a problem in your home, not to mention a much cleaner method.

Ridding Your Home of Flies

When you have a fly issue in your home, you need a reliable means to dispose of them quickly and effectively. There is no better way to rid your home of flies than to use their natural instincts against them. Dr. Killigan’s The Fly Inn ™  is a fly trap that is placed within a windowsill. It relies on natural UV light to attract flies to the window and then instinct to lead them to the glue strip. The flies climb in, and they are trapped and hidden inside. The best part is the front of the trap has a pleasing design so no one will think twice if you have a pest control device in place – you can place it with confidence.

The Fly Inn ™  is a proven method to rid your home of flies. Our team of professionals is dedicated to perfecting the art of Killing Them Softly™. We have designed a fly trap that is not only safe, but it is also created with style, restoring peace of mind and returning “classy” to your home.

We are continually raising the bar in toxin-free pest control remedies. All our products come in a design that is pleasing to the eye and carries a 100% satisfaction guarantee. If you are not satisfied for any reason, contact us, and we will not hesitate to make things right.