From wikipedia:
A tarantula hawk is a spider wasp (Pompilidae) that preys on tarantulas. Tarantula hawks belong to any of the many species in the genera Pepsis and Hemipepsis. They are one of the largest parasitoid wasps, using their sting to paralyze their prey before dragging it to a brood nest as living food; a single egg is laid on the prey, hatching to a larva which eats the still-living host. They are found on all continents other than Europe and Antarctica.
The female tarantula hawk wasp stings a tarantula between the legs, paralyzing it, and then drags the prey to a specially prepared burrow, where a single egg is laid on the spider's abdomen, and the burrow entrance is covered.[3] Sex of offspring is determined by fertilization; fertilized eggs produce females, while unfertilized eggs produce males.[3] When the wasp larva hatches, it creates a small hole in the spider's abdomen, then enters and feeds voraciously, avoiding vital organs for as long as possible to keep the spider alive. After several weeks, the larva pupates. Finally, the wasp becomes an adult and emerges from the spider's abdomen to continue the life cycle.