Why do hanging bags if water keep flies away?

Hanging bags of water are believed to deter flies due to the way light refracts through the water, which can confuse and disorient them. The shimmering surface creates a visual effect that is thought to be unappealing to flies, making them avoid the area. Additionally, some theories suggest that the reflections mimic the presence of predators or other insects, further discouraging flies from approaching. However, scientific evidence supporting this method's effectiveness is limited.