Insects that are armed with powerful stings are often strikingly coloured to warn off potential predators – a strategy known as aposematism . A good example of this is the black and yellow colour pattern of the European wasp (Vespula germanica).
Some harmless insects take on the appearance of aposematic insects even though they are not actually dangerous themselves. Hover flies are an example of this. One common hover fly species – the drone fly Eristalis tenax – is an excellent bee mimic, and was the star in a recent ‘one minute bugs’ video (link).
Other common hover flies (image below) are harmless flower visitors but their striking yellow and black markings superficially resemble the markings of bees or wasps. Bees and wasps usually have stings and consequently are left alone by many predators. Hover flies don’t have stings, so by adopting colour patterns similar to bees and wasps this affords the hover flies some protection. This defence strategy is known as Batesian mimicry.