The name makes this insect sound like it is a bird, but the tarantula hawk is actually an insect --a large and beautiful wasp. The tarantula hawk (also called a pepsis wasp) is one of the few insects that can take on a tarantula and win. Tarantula hawks are up to four inches long with a blue-black body and bright rust-colored wings. Their long legs end with hooked claws for grappling with their victims. The stinger of a female tarantula hawk can be up to 1/3 inch long. The sting, particularly of Pepsis formosa, is among the most painful of any insect.

Like many other wasps, the tarantula hawk's preferred food is nectar. However, it is the female wasp's quest for a food source for her young that puts tarantulas in danger. In the spring after mating, the female wasp prepares a hole in the ground and goes in search of a tarantula. This is a challenge: the tarantula is out and about at night, but the wasp is active during the day when the tarantula is underground in the silk-lined burrow it has built for itself.

At the entrance to the burrow are strands of silk which, when disturbed, let the tarantula know that a potential insect meal is passing by. The tarantula hawk searches until it locates a tarantula's burrow, probably by smell. It vibrates the silken trip lines to alert the spider and lure it out. When the tarantula comes out, a swift battle takes place in which speed and precision determine which is the predator and which is the prey.

When the spider rears up on its back legs to defend itself, the wasp must quickly sting the nerve center on the spider's underside. If she is successful, the tarantula is alive but paralyzed. A dead tarantula is of no use to the wasp. Next, the tarantula hawk drags the paralyzed and helpless tarantula back into the hole she has prepared. She lays a single egg on the spider's abdomen, seals the entrance to the burrow, and leaves, never to return.

The spider lives on as the only food source for the developing wasp larva. When the egg hatches, the larva gradually consumes the tarantula, carefully avoiding eating any vital organs which would kill the spider. The tarantula can live for many months this way. Eventually the larva pupates next to what is left of the spider and spends the winter. In the spring it emerges as an adult tarantula hawk, ready to begin the cycle again.

Tarantula hawks live in the southwestern United States. They belong to the family Pompilidae, the spider wasps, and are the largest in size in this group. Male tarantula hawks do not have stingers and thus are not a danger to tarantulas, but they are protected by their bright warning coloration and unpleasant smell.