Novomessor ensifer is a species of ant endemic to Mexico. A member of the genus Novomessor in the subfamily Myrmicinae, it was first described by Swiss entomologist Auguste Forel in 1899. N. ensifer was originally a part of the genus Aphaenogaster until a recent phylogenetic study concluded that Novomessor was genetically distinct and should be separated. The ant is a medium-sized species, measuring 5.5 to 10 millimetres (0.2 to 0.4 in). The ant is ferruginous-colored in some certain parts of the body, and small workers (nanitics) in incipient colonies are noticeably different in color and body structure.

N. ensifer is active throughout the day, where they forage on the ground and sometimes on low herbs. Colonies are found under stones and other objects in tropical dry forests and pine-oak forests. These ants are solitary foragers and predominantly feed on insects such as wasps and moths. The only known predator of N. ensifer is the giant horned lizard (Phrynosoma asio). While nothing is known about its reproduction, nuptial flight may take place during spring or summer, where queens establish their nests under stones and other objects.

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