Monomorium floricola is a minute, colorful, glassy smooth species. In the field, it can be spotted by it's elongated, shining black body that is often lighter in the middle section. Colonies are capable of recruiting in high numbers to baits and natural food resources, and the species often invades habitations. Closer inspection reveals a sparse scattering of erect white pilosity, an elongate head, and a relatively long petiolar peduncle.
Diagnosis of worker among Antkey species. Worker caste monomorphic. Head shape ovoid. Antenna 12-segmented. Antennal club 3-segmented. Antennal scrobe lacking. Antennal insertions at least partly covered by frontal lobes; not surrounded by a raised sharp-edged ridge. Frontal lobes do not obscure face outline between mandible and eye Antennal scapes not conspicuously short; easily extended beyond eye level. Posterolateral corners of head unarmed, without spines. Eyes medium to large (greater than 6 facets); distinctly less than half head length. Mandibles triangular. Mesosoma with erect hairs; shining smooth lacking any areas covered with punctate sculpture. Pronotal spines absent. Propodeum lacking spines or teeth. Waist 2-segmented. Petiole with peduncle; lacking large subpetiolar process. Petiole length greater than petiole height. Postpetiole not swollen, in dorsal view not distinctly broader than long or distinctly wider than petiole. Color shiny and bicolored with dark brown to black head and gaster and paler red or yellow mesosoma, waist and appendages. In some specimens the paler portions are only weakly distinguishable from the head and gaster.
Among introduced and commonly intercepted Monomorium, M. floricola can be distinguished from M. destructor, M. pharaonis and the M. salomonis group by its glassy smooth integument that lacks sculpture even on the mesosoma. Among smooth and shining Monomorium, M. floricola is distinguished from M. liliuokalanii by the petiole shape (which is distinctly longer than tall in profile) and from M. ebeninum by the dark brown to black head and gaster and contrasting paler red or yellow mesosoma, waist and appendages (versus uniformly dark brown to black).