I’ve noticed something interesting that I cant get an answer to online. Whenever I leave out watermelon in my house (After eating it of course. I cut slices from the melon so what gets left behind is the rind), it attracts lots of gnats and flies without failure. After cutting and eating a Yellow Watermelon for the first time and then leaving it out, There wasn’t a single fly that cared for it, it was never swarmed or landed on or fed upon. it just sat there for a day or so before I finally threw it out.

Why is this?? Repeating this same scenario always gives me the same output. The flies aren’t attracted to the Yellow Melon, Why?