Pompilidae Wasps are commonly called spider wasps, and there are more than 4,200 species split into 4 subfamilies. All spider wasps are solitary, and most capture and paralyse prey.
Females spider wasps are often larger than the males, with coloring and wing appearance varying greatly among the many species. Black is the most common colour, with contrasting aposematic markings of orange, red, yellow, or white also being fairly common.
As the name suggest, spider wasps capture and paralyse spiders and then use them as a host for feeding their larvae. Once paralyzed, the spider is dragged to where a nest will be built. A single egg is laid on the abdomen of the spider, and the nest – or burrow – is closed.
The size of the host can influence whether the wasp will lay an egg that will develop as a male or a female. When the wasp larva hatches it begins to feed on the still-living spider. After consuming the edible parts of the spider, the larva spins a silk cocoon and pupates – usually emerging as an adult the next summer.
Source, National Geographic and good old Wikipedia!