Vespa velutina or Yellow-legged Hornet is an insect native of South-East Asia, naturally distributed between Southern China, India, Indochina and Indonesia. For the effect of the geographical isolation of the different populations and the climatic diversity, Vespa velutina has differentiated into 11 subspecies, but only the northernmost subspecies, Vespa velutina nigrithorax (du Buysson, 1905), was accidentally introduced from China to other parts of the world. The introduction areas are South Korea in 2003, Europe in 2004 and Japan in 2012.
The first report of the presence of Vespa velutina in Europe was in 2004 in France, near the city of Bordeaux. Probably the introduction was caused by a single queen transported by a cargo ship from the Chinese provinces of Zhejiang and Jiangsu. In the following years the species has spread rapidly in the French territory colonizing most of the nation. In a few years the species has spread also in neighboring countries, colonizing Spain, Portugal, Belgium, Italy, Germany and Great Britain. In Italy, the species arrived in 2012, when some adults were captured in Liguria, near the cities of Ventimiglia and Loano. In 2013 the first nests were discovered, five in the western part of Liguria and two in the province of Cuneo in Piedmont. The nests observed in Liguria increased to 50 in 2014 and at least 221 in 2015. In 2016, the species is still expanding in Liguria; in Southern Piedmont, however, the observations are currently sporadic. In any case, considering the climatic similarities with the French territory already colonized by Vespa velutina , it is reasonable to believe that in the coming years, the species could also spread in the eastern part of Liguria, Piedmont and neighbouring regions, such as Lombardy, Tuscany and Emilia Romagna. In the medium term the species might also colonize the central and southern part of Italy, by natural diffusion or passive transport of some fertilized queens, and thus become an issue at a national level.