Oregmopyga davesmithi Miller and Stocks n. sp. collected on grass (Poaceae) from Arizona and Mexico is described. Keys are included for the separation of Oregmopyga species based on the adult female, second-instar male, second-instar female, and first-instar nymph. Detailed illustrations and descriptions are included for the adult female, second-instar male, second-instar female, and first-instar nymph of the new species, which is most similar to O. tippinsi Miller and Miller.