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mountain digest (zimbabwe)

Magazine of the Mutare Publicity Association - January 2003

Hoverflies of the Bvumba

In the 1960s Bvumba farmer David Cookson collected 440 specimens of hoverflies, most from his home on the estate Laurenceville and a nearby farm Cloudlands. From these specimens 63 species were later identified and named by taxonomists. This remarkable collection was donated to and today sits in the Natal Museum in South Africa.

This collection is significant because it is one of the few large collections of hoverflies gathered by an individual from a single location in Africa, and the only extensive collection from this particular area. David Cookson collected most of his specimens between April 1963 and May 1966. Since then, no further research as extensive as this has been carried out in this locality.

In 1998, Andrew Whittington, curator of Entomology at the national Museums of Scotland, presented a paper describing a new species of Paragus found in 1965 within the Cookson collection. It was named Paragus (Pandasyopthaimus) cooksoni in honour of its finder.

The inventory of all these hoverflies drawn up by taxonomists from David Cookson’s collection aids entomologists in determining the distribution of Syrphidae in Africa. (Hoverflies belong to the Order Diptera i.e. all those insects that have only one pair of wings, that is, flies; and the Family Syrphidae.) The collection provides a basic list of species from Bvumba.

Any data regarding these creatures in Africa is very sketchy, but what is obvious from the data gathered is that it is extremely important for the Bvumba to be conserved for their survival.

Syrphidae have varied habitats and of course habits. Most are brightly coloured attractive beasties, sometimes striped, spotted or banded, the general background colour being yellow or and black. They are often seen motionless, suspended in the air, wings vibrating rapidly, hence their name.

So what? Who cares about the survival of hoverflies nobody even notices — apart from the fact that some resemble bees? It is a bit of a cliché, but we all know that without the little things in life, the bigger things suffer. Paragus hoverflies, which live in partial shade in thick woodland scrub, are excellent pollinators. Equally importantly, their larvae feed on aphids, so should be popular among gardeners and farmers, although many people are unaware that these small flies do anything significant. They are actually very efficient pest controllers.

Some types of hoverflies out-perform native bees in pollinating fruits in orchards: other species’ larvae also eat scales, thrips and caterpillars. Their closest predatory rivals are ladybirds and lacewings.

Other interesting facts: Americans call them Flower Flies. They range in size from 4 mm to more than 25 mm. They feed in great numbers on flowers, which also act as nuptial beds (or, more technically - mating sites). The only places you will not find hoverflies are in arid regions and the Arctic and Antarctic

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