GARDEN HOVERFLIES

Brett Westwood

Recently I moved to Stourbridge, to live in the network of Victorian terraces and semi's close to the town centre. With their extravagant poetic licence, local estate agents call the area the "Old Quarter" which to me has exotic overtones of Baghdad or Jerusalem. The far from exotic reality is a network of long thin gardens with some established trees and shrubs and neatly cropped lawns. I hate mowing , so most of the grass I inherited has become flowerbeds and a table-top sized wildflower "meadow ". In a rare fit of enthusiasm I also dug a tiny pond, which attracted a southern hawker to oviposit on the day after it was filled.

In 2001 and again in 2002 I kept an informal record of the hoverflies which appeared in the garden. Most I could have predicted but there were a few surprises too. First to appear are the Eristalis droneflies, both E. tenax and E. pertinax which seem to be active even on midwinter days if there's enough sun. They are closely followed by another over-winterer, the Marmalade Hoverfly Episyrphus balteatus. Numbers of this species build up throughout the summer, boosted by immigrants, until it becomes one of the most regular species in the garden. By mid April, large "bumblebees" buzzing round the Spanish bluebell leaves turn out on closer inspection to be Narcissus Flies Merodon equestris. The adults come in two colour forms in my garden, a black and orange version which mimics the red-tailed bumblebee, and a tawny one which looks rather like the carder bee Bombus pascuorum. They lay their eggs on the bluebell leaves and the hatching grubs burrow into the bulb tunics.

As spring turns to summer, the hoverfly total mounts. In the last two years, I've been surprised to see the unmistakably dapper species Xanthogramma pedisequum which is testament to how badly I take care of the lawn. This smart citrus and black fly hovers very low down in long grass looking for flowers or possibly ant nests in which its larvae have sometimes been found. This June saw another surprise in the form of Chrsyotoxum festivum, a superb wasp mimic with curved yellow bars on its abdomen and yellow stripes on its thorax. It hovers a few feet above the ground, changing station every few seconds or so and is hard to observe until it settles. Like Xanthogramma, larvae have been found in ant nests, which means that mature gardens are a good place to look for the adults.

Mature hedges and dappled shade under trees in gardens stand in for the woodland edge habitats preferred by many hoverflies and a morning stroll down the garden reveals several species sunning on the Forsythia shrubs. In May I normally find Epistrophe eligans looking rather like a small drone fly with a shining bronzy thorax. In mid June Dasysyrphus albostriatus appeared, a classic wasp mimic with parallel whitish bars on its thorax, and soon after Leucozona lucorum, with a black and cream abdomen. One woodland edge species which may have bred in local compost heaps is Xylota segnis which has a black and gold abdomen and banded black and white legs. It rarely visits flowers unlike the large fly Volucella pellucens which spent several days on the globe heads of Allium christophii. This species lives up to its name when it hovers in bright light: you can see through the white translucent upper half of its abdomen. Using the hedge and the layer of duckweed on the pond was Helophilus pendulus.

As summer turns to autumn, migrants build up. Lots of Marmalade hoverflies are joined by Syrphus ribesii which spend their time in the sycamores at the end of the garden. The undersides of the leaves are coated in aphids by midsummer which explains the attraction. The yellow-dusted Myathropa florae is common in small numbers. Spires of late-flowering Mullein proved a real hoverfly Mecca in late 2001, drawing in the migrant Scaeva pyrastri, striped like a zebra, and Syritta pipiens, plus a number of syrphids which I lazily didn't identify. All the species I've seen so far are relatively easy to name , especially if you're armed with British Hoverflies ( Stubbs and Falk 1983, 2002) , but I suspect I'm missing the hovers which are a lot more bovver ….. they 're a challenge for next season