This is a Tarantula Hawk Wasp, and it is hunting for a tarantula, but it will not eat it. The adult wasps eat nectar and fruit. Instead, it stings the spider to paralyze it, and then drags it to a burrow. The wasp then lays one egg on the body. When the egg hatches, the larval wasp eats the living spider, being careful to save the vital organs for last, so that its food supply will stay fresh until it has finished eating.