If you have a garden or backyard with a few plants you will almost certainly see, between March and October, small yellow stripy flies hovering over your flowers. Most of these will be hoverflies, called ‘flower flies’ in the USA because of their attraction to wild and garden flowers. Their stripy appearance makes them look like wasps, which is almost certainly an evolved defence strategy: few predators, be they birds, insects or humans, like to swallow a wasp! But hoverflies can’t sting, are usually slimmer and smaller than wasps and have shorter antennae.
Most adult hoverflies feed on nectar and pollen – hence their love of flowers. They are not only excellent pollinators but many hoverfly larvae do a good job of hoovering up some of the aphids and grubs that are the enemies of our prized flowers and vegetables. Hoverflies are our friends.
We rarely observe their larvae (some of which live in garden and other ponds) but adult hoverflies can be seen everywhere where there are flowers in the summer. Of the world’s 6000 species of hoverfly, 260 have been recorded in the UK, some of which migrate from Europe each year. This year at St Nicholas Fields some 15 of the larger and more recognisable species of hoverfly have been identified and photographed (all the pictures in this feature were taken on the reserve), and we have also observed a number of the smaller and more elusive ones. Sadly, unlike butterflies and moths, only a few of those 260 hoverflies have common English names but this year at St Nick’s the out-and-out winner is the aptly-named Marmalade Hoverfly, Episyrphus balteatus. It darts restlessly to and fro in front of you, eventually settling on a flower to drink nectar or feed on pollen.
Another hoverfly frequently seen on the reserve is Helophilus pendulus. It gleams brightly in the sun as it it settles on a leaf or flower head, and is easily recognised by its tiger-like stripes which travel vertically down its thorax and horizontally across its abdomen. Also frequently-seen is Syrphus ribesii. There are elegant slim-bodied hoverflies of the Sphaerophora species and large plump ones with brown and white abdomens called Volucella pellucens. Drone flies (Eristalis pertinax) frequent the flower heads of the tall hemp agrimony around the Environment Centre pond, while one fairly large hoverfly also seen around the pond – Myathropa florea – sports an unmistakable Batman logo on its thorax. Among the lower plants growing round the edges of the pond can be seen a large hoverfly called Sericomiya silentis, sometimes mistaken for a hornet wasp.
Hoverflies are as much part of the British summer as ice cream and sandcastles but since they flit hither-and-thither, hardly stopping to draw breath, sharp eyes are needed to pin them down. It’s worth persevering, if only to say ‘thank-you’ both for the good they do in our gardens and for the pleasure they bring us every summer. Next time you flap a wasp away take a closer look: it might be one of the friendly and more dainty insects called hoverflies.