The Proliferans were a species of sentient non-humanoids who resembled large red ants. They were excellent at digging, often using their skills to dig under enemy forces and waylay them when they got close. They had their own empire, known as the Proliferan Empire which was in turn ruled by a monarch. At the time of the Galactic Civil War, the ruler was Queen Yentuki.
Sources
"The New Rogues Gallery: Unsung Heroes of the Rebellion" — Polyhedron 59 (First appearance) (Unlicensed)
"The Living Galaxy: Flawed Gems Shine The Brightest" — Polyhedron 63 (Picture only) (Unlicensed)