In several "farm kiln chicken" food stalls in Nan 'ao, Shenzhen, transparent water bags are hung to drive away mosquitoes and flies. Mr. Huang, who has been engaged in "farmhouse music" management for many years in Yishangou, Banba Village, Longgang District, said that this method is used by every family and I don't know who invented it. The method is simple: take a strong plastic bag, fill it with tap water and hang it around the food stall.

As for the principle of driving away flies, Mr. Huang said that the eyes of flies have the function of magnifying glass, and the light reflected by water bags magnifies the image of flies many times like a mirror. At the same time, the light from the water bag stimulates its eyes-the fly scares itself, so it doesn't dare to go near the water bag.

Tian Suixing, a biology teacher at Futian Middle School in Shenzhen, said that it may be because the transparent water bag has a convex lens. When the light passes through the "convex lens", it will definitely change the surrounding light intensity and temperature, and this change just stimulates some sensitive organs of flies, so keep a distance from flies. Regarding whether the magnifying glass scares away flies, tian teacher said that it is not true in theory.

In fact, hanging water bags to drive away mosquitoes and flies is not the original creation of Shenzhen "farmhouse music". In Hong Kong, Macao and Taiwan, many meat stalls and fruit stalls will hang water bags around their business premises to drive away mosquitoes and flies. Experiments show that the refraction of water in the water bag can really drive away mosquitoes and flies, and it is found that purple water is better in the water bag.