Vespa velutina, sometimes known as the ‘Asian hornet’ is an invasive non-native species from Asia. If you find one you MUST report it. It arrived in France in 2004 and has spread rapidly. As a highly effective predator of insects, including honey bees and other beneficial species, it can cause significant losses to bee colonies, other native species and potentially ecosystems
It is expected that the places it is most likely to be found in numbers are in southern parts of England (it may be able to cross the channel from France) or in goods among which it could be accidentally imported (such as soil with imported pot plants, cut flowers, fruit and timber). Active between April and November (peak August/September).
Further information on the Asian Hornet, including how else to report a sighting, can be found here