Keep flies out of your house with this simple trick as UK on brink of 'mini-heatwave'

The UK is set to bask in , with the latest and forecasts predicting temperature highs of 24C on Wednesday.

But the can bring unwelcome guests to our doors, in particular, the annoying house fly. As well as creating an annoying buzz house spread germs, they act as vectors, picking up pathogens like bacteria, viruses, and parasites from unsanitary environments like waste and decaying matter. These pathogens can then be transferred to food, surfaces, and even people when the flies land and feed. However, there is one tried and tested way to deter the unwanted visitors - and it doesn't involve any nasty chemicals. Everything you need you will already have in your .

All you will need is clear plastic ziplock food bags, water and a few pennies. Any coins will do.

Ziplock bags filled with water and even a few pennies at the bottom hung in your porch or around open windows and doors should keep them out.

The theory behind using bags of water with pennies to repel flies is that the reflected and refracted light from the pennies and the water confuses flies' compound eyes, causing them to fly away, according to howstuffworks.com

They say: "Flies have many small lenses in their eyes that are sensitive to light changes, and the distorted light from the bag is thought to disrupt their vision."

The technique is popular in restaurants abroad. Perhaps on holiday you have seen clear, water-filled bags hanging on the doors or cinched up in the outdoor dining area. These hanging bags are all about driving pests away. People hang these bags outside their homes, businesses and even in their barns to drive flies away in hot countries.

According to howstuffworks.com "various takes on the water-bag practice exist. Some advocates insist the bag must have flakes of floating tin foil; others say a penny or two. A couple of industrious websites even offer commercial takes on the concept, selling specially designed water bags to be used as repellents."

The explanations offered are that the flies perceive the clear liquid as the surface of a body of water or the insect flies away at the sight of its own magnified reflection. But the most popular reasoning that pops up among entomologists and patent-filing entrepreneurs is light refraction.

The website says: "Refraction takes place when a clear or opaque object, such as a piece of glass or a bag of water, alters the course and velocity of light. The rays of light, which normally travel in a straight line, bend. This effect is responsible for some optical illusions, such as mirages, that occasionally baffle humans as well.

"In theory, refraction can be just as confusing for some species of insect, especially the housefly. It boasts a highly sensitive array of eyes that allow it to see in multiple directions at once."

The insect's head mostly consists of a pair of large, complex eyes, each of which is composed of 3,000 to 6,000 simple eyes. These eyes can't move or focus on objects like human eyes, but they provide the fly with a mosaic view of the world around it.

Each simple eye provides one small piece of the puzzle, much like the way a screen's pixel delivers one detail of the larger picture.

A housefly bases its sense of direction on the direction sunlight comes from. Some entomologists suggest that when these complex, sensitive eyes experience refracted light, the insect becomes confused and flies away.

While some supporters claim water bags keep all kinds of flying insects away, most report success with complex-eyed insects, like houseflies.

One person online said: "I tried the zip lock bag and pennies this weekend. I have a horse trailer. The flies were bad while I was camping,' they said.

"I put the baggies with pennies above the door. NOT ONE FLY came into the trailer."

Another said: "I swear by the plastic bag of water trick. I have them on the porch and in the basement. They say it works because a fly sees a reflection and won't come around."