A new species of Lactura is described from Texas: Lactura rubritegula sp. n. Identity of the new species can be reliably determined by both larval and adult characters, CO1 haplotypes, and its late-spring period of flight activity. Male genitalic features overlap with those of L. basistriga (Barnes & McDunnough, 1913), whereas female structures differ markedly between the pair. The new Sideroxylon-feeding species, rare in collections, is found principally in limestone areas in the vicinity San Antonio, Texas, westward through the southern Hill Country. We illustrate the adult and larval stages and male and female genitalia, review available DNA barcode data that support the recognition of the new Lactura, and briefly characterize its life history.