Our work concerns two important invasive termites: Coptotermes formosanus – a native of China, introduced to Japan, Hawaii, and the U.S. mainland; - and Reticulitermes flavipes – a native of the U.S., introduced to France, Germany, Canada and Chile. Using microsatellite and mtDNA markers, we addressed two major questions: 1.) what is the source location(s) of introduced populations? and 2.) is the invasion success of these species related to changes in social organization similar to the formation of supercolonies in some invasive ants? Our results indicate that Louisiana is the likely source of introduced French populations of R. flavipes, whereas southern China may be the source of C. formosanus populations introduced to the U.S. Introduced populations of both species showed reduced genetic diversity compared to native populations. Introduced colonies of R. flavipes in France exhibited characteristics similar to unicolonial populations of invasive ants: they had much higher numbers of reproductives, underwent more frequent colony fusion, and were spatially more expansive than colonies in the native range. However, introduced populations of C. formosanus did not show such characteristics. These results suggest that a breakdown in colony boundaries leading to large unicolonial populations may be a factor in the invasion success of some but not all invasive termites.