We conducted phylogeographic studies using nuclear microsatellite markers and mitochondrial DNA sequence data to determine potential source populations for two successful termite invaders: Reticulitermes flavipes, native to the USA, and Coptotermes formosanus, native to China. We also characterized colony breeding structure to determine whether their invasion success is associated with shifts in breeding structure with more reproductives and larger colonies, as seen in many invasive ants. Our results indicate that introduced populations of R. flavipes in Europe and Chile likely originated from New Orleans. Colonies in introduced populations have more reproductives and are larger than those in the source population. Introduced populations of C. formosanus in Japan and the USA appear to be unrelated and likely arose through separate introductions. We are unable to identify specific source populations in China, although southern China is probable. Colony breeding structure in this species is highly variable and introduced populations show no pattern of having greater numbers of reproductives. Thus, a shift to larger colonies with more reproductives may have played a role in the invasion success of R. flavipes but not C. formosanus.