The Superfamily Coreoidea: There are more than 3300 species of these insects worldwide, and male hind legs are impressively diverse in shape. Males in many species (but not all) use their hind legs as weapons to wrestle over plant territories where females visit to mate, feed, and lay eggs.
Here are two male leaf-footed cactus bugs, Narnia femorata, wrestling over a territory on a nearby cactus. Males fight in intense bursts, use a variety of fighting maneuvers, and they obtain numerous injuries. Their combat behavior is a lot like mixed martial arts fighting in humans. And, below you can see the variety of shapes, sizes, and colors in this insect superfamily.