Pepsis grossa, formerly and perhaps better known as Pepsis formosa, is a very large species of pepsid spider wasp from the southern part of North America, south to northern South America. It preys on tarantula spiders, giving rise to the name tarantula hawk for the wasps in the genus Pepsis and the related Hemipepsis. Only the females hunt so only they are capable of delivering a sting, which with that of the bullet ant is considered the most painful of any insect sting scoring 4.0 to the bullet ant's 4.0+ on the Schmidt sting pain index. It is the state insect of New Mexico. There are three colour morphs, the xanthic orange winged form and the melanic black winged form. In northern South America there is a third form, known as "lygamorphic" which has a dark base to the wings which have da