Although these brightly-coloured insects look like bees or wasps, they are in fact true flies and do not sting. Hoverflies are excellent examples of Batesian mimicry (named after H W Bates who first described it in 1862). They generally mimic bees and wasps – insects that sting and also taste unpleasant, so are avoided by predators. Drone-flies mimic honey bees, Volucella bombylans (pictured) has several different forms mimicking bumblebees, while others species are very convincing wasp mimics.
There are about 250 different hoverfly species in Britain. You can generally see plenty of adults on flowers throughout spring, summer and autumn. Hoverfly larvae are varied too – some even resemble small slugs. They all have different feeding habits. For example they may eat plants, feed on rotting wood and fungi, attack bulbs or parasitise other insects.
More well known and welcome in the garden are those that eat aphids and other pests eg Syrphus spp. Rat-tailed maggots, larvae of the dronefly Eristalis tenax, are found in polluted pools and extend their tail breathing tubes to the surface to breathe.
What does it eat?
Adults eat drink nectar and eat pollen and honeydew. Some species feed on dead insects. The larvae of different species eat different things. Some eat aphids.
When will I see it?
Between March and November, depending on the species.
Where will I see it?
Hovering near and resting on flowers. Many seem prone to entering conservatories and greenhouses.
Information from RSPB