North America's 10 species of spider wasps in genus Auplopus are black wasps, usually with a bluish or turquoise sheen. Most species have reddish or honey-colored legs. There are at least three Auplopus species with all-black legs; these are very hard to tell apart.
Auplopus spider wasps typically snip off the legs of the spiders they capture, which makes them easier for these rather small wasps to lug around. They usually prey on sac, ground, crab, nursery web, or jumping spiders. They craft mud cells for their young to develop in.
Learn more about these and other spider wasps on their group page.