Flies, drain flies and fruit flies are some of the most annoying and dangerous pests in the world. Flies can carry an enormous number of dangerous illnesses and can easily cause food poisoning. If you have an issue with flies in or around your home you should act quickly to get rid of them.
Just over one hundred years ago a Nobel Prize-winning German scientist, Karl von Frisch, discovered that insects do not just see colour but have individual preferences for specific colours. He did this by placing down a coloured paper with bowls of sugar water to imitate flowers and seeing which colour the bee would land on. Every bee displayed a preference for colour as opposed to grey and each bee chose a different colour. Over time, it was realized that other insects can see light and have a preference for a specific colour, but it was not until the fruit and drain fly that we discovered that some insects are specifically attracted to the UV, or blue-violet, spectrum. That means blue and purple light attracts them more than other colours. This was first put to use by the United States military. They noticed a severe issue when working in war-torn, hurricane-damaged or simply poverty-stricken locations. The trash would pile up with nowhere to dispose of it and people would be living with thousands of flies. Each fly can carry up to a hundred dangerous diseases, many of which can be fatal without immediate medical attention. The military could not provide that level of care during such a severe time and so developed a new device using this research from over a hundred years ago. They took the normal fly zapper which is hued yellow and changed the light colour to be a blue-hued LED. This is what is called true blue light. Humans respond, like insects to changes in the base light of their environment. The day time is hued blue by the light of the sun filtered through our atmosphere. When the sun goes down the colour switched to a red hue. Using a blue screen computer or light such as LED’s will cause your body to perceive it as daytime which can confuse your body’s inner clock. This can also cause flies to be drawn to the colour, unlike cockroaches and bed bugs which are nocturnal, because flies are diurnal, which means they prefer the daytime to the night. This is how the device works. In the nighttime, it imitates the sun which draws flies towards it. The flies make contact with an electrically charged ferromagnetic net that shocks them to death. This has been so effective that the fly issue the military had was resolved almost overnight.
The same process can be done with UV light which works as well or better. The reason this works and why flies are attracted to these colours like blue and purple is because their visual spectrum is shifted from ours. Our spectrum is green-focused, which is the colour at the centre of our visual spectrum. The flies are blue centred with UV light being within their visual spectrum. That means the fly can see UV radiation which comes from electrical equipment as well. This means flies can see electricity, but thankfully do not seem to know what it is. What they do like is going towards UV light because it looks to them like the sun. By using either an electronic zap trap or a pesticide sprayed surface or both using UV hued light to kill flies is highly effective.
