Tetramorium tsushimae is a temperate Asian species, originally imported in the early 20th century to St. Louis, now found in urban areas of Missouri and Illinois. Winged sexuals are reared in spring, but most never fly, mating in the nest, the females remaining on as multiple queens. Note queen pupa and prepupa.
This ant is about 0.5 mm smaller in length than the common pavement ant and often has a reddish or yellowish brown mesosoma, as seen in some individuals by clicking to enlarge the image.