Human mediated transportation into novel habitats is a prerequisite for the 
establishment of non-native species that become invasive, so knowledge of common 
sources may allow prevention. The brown marmorated stink bug (BMSB, Halyomorpha 
halys) is an East Asian species now established across North America and Europe, 
that in the Eastern United States of America (US) and Italy is causing 
significant economic losses to agriculture. After US populations were shown to 
originate from Northern China, others have tried to source BMSB populations now 
in Canada, Switzerland, Italy, France, Greece, and Hungary. Due to selection of 
different molecular markers, however, integrating all the datasets to obtain a 
broader picture of BMSB's expansion has been difficult. To address this 
limitation we focused on a single locus, the barcode region in the cytochrome 
oxidase I mitochondrial gene, and analyzed representative BMSB samples from 
across its current global range using an Approximate Bayesian Computation 
approach. We found that China is the likely source of most non-native 
populations, with at least four separate introductions in North America and 
three in Europe. Additionally, we found evidence of one bridgehead event: a 
likely Eastern US source for the central Italy populations that interestingly 
share enhanced pest status.