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Hoverflies are fascinating, with a range of different life strategies and behaviours that help us better to understand the world around us. They do not sting or bite, nor do they contaminate our food. Many species are attractive to look at, with subtle shapes and often striking colours and patterns. They occur mainly in pleasant and even beautiful locations, and are particularly associated with flowers, from which they take nectar and pollen. Many can be found around the places where we live, work and travel, enabling us to enjoy them at odd moments, or while we are engaged in other activities, such as gardening. Hoverflies will reward even a cursory look, and yet can provide a lifetime of interest. What follows concentrates mainly on the adult insects, though their larvae are a subject of considerable interest in their own right.
Hoverflies come in a surprising variety of sizes, shapes and colours. As insects, they of course have six legs, and their bodies are formed of three main parts - head, thorax (from shoulders to waist) and abdomen (from waist to tail tip). The smallest of the 300 or so British species are barely bigger than a garden ant, and the largest near the size of a hornet. Some are slender, with elongated wasp-waists, and others are as stout as bumble bees. Many are plain black, and a few are pale whitish, grey or buff; but perhaps the majority show what many people would regard as the classic hoverfly colours - black with bright spots or bands of white, yellow, orange or red.
Particularly in this last group, hoverflies resemble stinging wasps or bees, which must give them some protection from predators. Unlike bees and wasps, however, hoverflies have two not four wings. Where this feature is not obvious (as when the wings are folded), a close look at a hoverfly will reveal large compound eyes, which take up most of the head and are often brownish or reddish in colour: bees and wasps have smaller, black eyes, of a curved, somewhat comma-like shape. Bees and wasps always have long and flexible antennae; those of most hoverflies are short, and in the uncommon cases where they are long, they show other obvious differences. However, the superficial resemblance to honeybees (for example by Eristalis hoverflies), to bumblebees (by Pocota or Volucella) and to wasps (by Chrysotoxum) is often very wonderful.
Distinguishing hoverflies from their relatives, the other true flies, is less straightforward, but not difficult with practice. Hoverflies never have long legs like craneflies or mosquitoes. They are often shaped more like house-flies or bluebottles, but these and many other types of fly have rather short wings, and there are obvious bristles on the thorax and abdomen. Most hoverflies generally have rather long wings, and while some look furry, none looks bristly. Just occasionally, what appears to be a metallic-coloured or brightly patterned hoverfly will turn out in fact to be a soldierfly; however, soldierflies are not nearly as common and obvious as hoverflies.
If the need arises, hoverflies can always be told by the unique pattern of veins in their wings, particularly the presence of a "false vein" which appears as a straight dark line near the middle of the wing, and is easy to see once you get used to looking for it.
A very good guide to what is a hoverfly is given by its behaviour. Most obviously, some species (though by no means all), regularly hover, holding position with remarkable steadiness and for much longer periods than other flies, or even than such accomplished flyers as dragonflies, bees and wasps. Note in particular that the familiar, tawny-coloured and furry bee-fly Bombylius major hovers beautifully, but it shows a long, permanently straight proboscis and is not in fact closely related to the hoverflies. Hoverflies are, above all, lovers of flowers and blossom. Often, on a hedge and verge in spring, or a garden border in summer, the majority of the flies present will be hoverflies. Watching and distinguishing them in such pleasant places is no particular hardship!
Some hoverflies are very easy to identify. Even from twenty metres away, there is no mistaking the large black and white Volucella pellucens as it hangs high in the woodland sunlight. A dozen or more common species can be identified with a quick glance as we walk past a flowerbed. Less readily identifiable hoverflies will often allow surprisingly close views. Particularly when they are feeding or basking in the sun; they will remain still as we gradually bring our eyes up close enough to see details. With some experience, dozens more can be identified in this way. It is also quite easy to catch hoverflies directly into a suitable transparent receptacle such as a jar or even a large glass tube: a cautious approach and a quick final movement will often do the trick. This of course enables a more prolonged study, without harming the fly.
The next logical step is to bring a hand-lens to bear; a magnification of ten times will enable fine detail to be seen. In this way, it will be possible to identify many additional species with some confidence. A butterfly net will bring more hoverflies into the tube for examination. In some situations (for instance when hoverflies are feeding on tall ivy), a pair of binoculars can be useful, but they are rarely truly necessary. Modern digital cameras allow some surprisingly good hoverfly images to be taken quite straightforwardly, often showing crucial identification features that can be studied at leisure. It must be said that some hoverfly identification requires the use of specimens and a microscope, but a very great deal can be done without going to such lengths.
Many general books about insects show illustrations or photographs of a few hoverfly species, and are definitely worth studying. However, a more specialised book is really needed if more than a few species are to be identified correctly, and the diversity of their lives properly understood. Here are the most significant of these books.
British Hoverflies: an illustrated identification guide by Alan Stubbs and Steven Falk, published by the British Entomological and Natural History Society, November 2002.
This substantial volume is the bible of British hoverfly enthusiasts, with an authoritative and readable text, and beautiful, mostly very helpful, colour illustrations of a great many species. The keys are clear, and with practice by no means difficult to use. (An earlier edition of this book may be found, but note that a many changes in, for instance, species' names, took place between editions, and it is far preferable to have the 2002 version).
Britain's Hoverflies. A Field Guide by Stuart Ball and Roger Morris.
This WildGuides volume was first published in 2013, and proved deservedly popular. A second edition, produced in 2015, corrects some errors in the first edition, and includes new material. Full of information, and with superb photographic illustrations, it will answer the questions of both beginners and seasoned veterans. An essential reference, great value for money, and the perfect companion to Stubbs & Falk.
Hoverflies by Francis Gilbert, published by the Cambridge University Press, and number 5 in their Naturalists' Handbooks series.
This is a slim, paperback volume, with a lot of interesting information, but with much less detail than Stubbs and Falk. It borrows some of the illustrations from the larger volume, and has its own key to a reduced number of species. A valuable reference, with some unique features, but if identification is your main aim, you will soon find it inadequate.
Hoverflies of Northwest Europe Identification keys to the European Diptera: Syrphidae by M.P. van Veen, in English, and published in Utrecht by KNNV Publishing in 2004, 2009, 2014.
This is an attractive hardback, mostly in the form of a detailed key, with fine black and white illustrations and a few colour photographs. For the observer based in Britain, perhaps its main advantage is to provide a useful cross-check (particularly using its illustrations) on any specimens still in doubt after working through the keys in Stubbs and Falk. For anyone looking seriously at hoverflies anywhere from northern France and Germany to Fennoscandia, this is the indispensable reference.
Colour guide to hoverfly larvae by Graham Rotheray, published by Derek Whiteley, Sheffield, 1993.
Hoverfly larvae are not as readily found as those of, for instance, butterflies and moths. For people with a general interest, this book is by no means essential, but it is the definitive reference for those who study these often colourful and sometimes bizarre creatures.
The Report of the Recorder (N. F. Janes) in Bedfordshire Naturalist No. 38, pages 61-64, published in 1985, contains a very interesting and useful list of the county's hoverflies in that era.
The World Wide Web is always worth checking for hoverfly sites, but the best and most relevant is certainly that of the national Hoverfly Recording Scheme which contains information on each species, up-to-date maps of distribution, colour photographs and much else besides.
Not everybody is happy with using scientific names. They can be hard to remember, and even experts differ markedly on how they are to be pronounced. However, except in the case of the very few species with recognised English names (most of which are listed below) there is no other realistic way of referring to our hoverflies. When getting to know them, there is of course nothing to stop an observer from inventing his or her own informal names for individual species or similar-looking groups of flies, such as ‘furry orange’ or ‘thin yellow and black’. In this way, our own first impressions will help us to remember features, note them down, and gradually make sense of the different families. The scientific names can then steadily be learnt. One day there may be accepted English names; indeed, there seems at present to be a growing tendency to coin them. However, to devise clear and unambiguous names is a significant challenge. In addition, of course, we would still need to know the scientific names in order to communicate with the many experts working outside the UK.
Drone-fly for Eristalis tenax - because of its resemblance to a male (drone) honeybee.
The Large or Greater Bulb-fly for Merodon equestris because its larva is pest of bulbs in horticulture.
Lesser Bulb-fly for one or more species of Eumerus for the same reason, and these species being significantly smaller.
These few well-established examples of English names actually illustrate the naming problem rather well. The Drone-fly is one member of an extensive family, many of which look like honeybees; if the others in the family are to have English names it would make sense to call them all drone-flies, and we would then have to devise suitable qualifiers (in a similar way that we do, for example, for Song and Mistle Thrushes). The Greater and Lesser bulb-flies mentioned above are not actually closely related to each other, and should logically have rather different names to reflect this. From these few examples, it can be seen what a challenge it would be to arrive at a meaningful and logical set of English names.
One English name that seems to be catching on is for the common and widespread species Episyrphus balteatus. This is now often called the Marmalade Hoverfly, presumably for strand-like bars showing against its orange abdomen. Well, what the name lacks in gravitas it certainly makes up for in originality and popular ap-peel!contact details
Bedfordshire County Hoverfly Recorder
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