These insects are in the garden in conjunction with the Cicada Killer Wasps.
Red Velvet Ants are actually wasps, the females do not have wings. They are big – close to 2 inches long. They are not aggressive, but the female can deliver a excruciatingly painful sting if disturbed (I wouldn’t wear flips flops in the garden). We see them because they prey on ground nesting bees and wasps (i.e. cicada killers).
The female finds larvae cicada killers in their burrows and injects an egg….its gruesome in the insect world.
So again, the females are the ones to watch. The sting is supposed to be incredibly painful. They aren’t after you, they’re after other wasps. Just be careful where you step.