Fruit flies are attracted to many types of fruits, wine, vinegar, etc.
1. First cut away the top conical part, then throw in some fruit discards such as grape stalks, pieces of pomelo skins, or vinegar. Try different types of food to see which will attract these flies.
2. Cover the top opening with a clear film such as Reynolds.
3. Use a sharp pointed stick to poke a small hole just big enough for a fly to crawl in.
4. Set the bottle in a place where you want to trap them
The principle is flies have an acute sense of smell and can home in on them until they find it. They will crawl through the hole to reach the fruit but later cannot find the hole to leave as the bottle is transparent. They will crawl or fly about aimlessly until we choose to throw away the bottle and make another trap.
