These are adult forms of Zebra caddisflies (Macrostemum zebratum). They barely eat and live only couple of weeks. Only thing they do is fuck, as much and as fast as they can. Life is short, you must try everything.
Before becoming adults they spend most of their lives as larvae crawling on the river bottom eating garbage and building houses out of junk. Once again we can see how creative mother nature is. How much we can learn from it. Even if you hit rock bottom it's not a reason to stop being creative.
Google images "caddisfly larvae case" you'll be amazed how extremely beautiful they are.