These are our largest wasps. Until recently the indigenous variety, the European hornet (Vespa crabro), was comparatively rare in Britain and confined almost exclusively to the South East. But over the last two or three decades it has spread north and west into the Midlands and South Wales, probably due to global warming.
This summer, for example, I came across two or three healthy individuals in Oxfordshire during the last weekend in August.
Hornets have one of the most toxic stings in the insect world, but even so the doses administered are so small that they are not serious – effectively being like a very nasty wasp. Multiple stings can be a different matter however, particularly when from some of the biggest south Asian species or when the victim has an allergic reaction.
Despite this, hornets are our allies, not threats to humans. In common with wasps for most of their life-cycle they are largely carnivorous, feeding their larvae on protein-rich insects (many of which are serious agricultural pests). It is only in late summer when the next generation has matured and left the colony that the workers turn to sugar-rich foods where they begin to clash with humans in orchards and at picnics.
As so often, however, there is a note of warning on the horizon. While European hornets can exist in an ecological balance with their native insect prey which has been honed over countless millennia, climate change means an Asiatic relative (Vespa velutina nigrithorax). This is slightly smaller than our hornet, but it has a more powerful venom and is particularly drawn to prey on bee colonies. The latter have been devastated over the last couple of decades by the parasitic varroa mite and sudden colony collapse disorder – the Department of Environment. Farming and Rural Affairs (DEFRA) warns an invasion by alien hornets could be the last blow.