Flies

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Flies, known technically as diptera, have a single pair of wings and are the dominant insects in many habitats. The group includes just a few species that are highly damaging to man and to wild and domestic animals by carrying diseases – malaria being the prime example. But the order also includes some, such as hoverflies, that are beneficial.

Hoverfies are so called because they are able to hover in mid-flight. There are many different species, often looking like bees or wasps for self-protection. Unlike bees and wasps which have two pairs of wings and a distinct 'waist' where their thorax meets their abdomen, hoverflies, like all flies, only have one pair of wings, no waist, and no sting.

Adults feed on nectar like bees, so are valuable as pollinators. The young of many species feed on aphids, so it is a good idea to try to attract them into your garden. (Try growing annuals like candytuft or poached-egg plant or perennial verbenas.) Some, however, like the bumblebee hoverfly, lay their eggs in bee or wasp nests, where they scavenge within the nest, and one, the narcissus fly is regarded as a garden pest, because its young eat bulbs.

Hoverflies vary considerably in size. The largest, like both the two last mentioned, are as big as bumblebees and look very similar, whereas the smallest, like the marmalade hoverfly, are only a few mm long.

The dronefly, which mimics the honey bee, is one of the commonest hoverflies, appearing from late spring and throughout the summer wherever there are flowers. Another common species, the banded hoverfly, is very wasp-like.

Of the myriad other species of fly found in Britain, probably the bluebottle and the crane fly are the most familiar, the former because it is often found in houses and the latter – known as 'daddy long legs' – because it is often seen flying round drunkenly in gardens.

Many flies are parasites, laying their eggs in or near their chosen hosts, but some, like the empid fly and the hornet robber fly are hunters, preying on other insects. Another particularly interesting fly is the bee fly, so called because it is furry like a bumblebee. It is most noticeable in spring feeding on flowers such as primroses and violets.

All the above are 'true' flies, belonging to the order Diptera, but a number of other insects are also referred to or seen as flies, such as the scorpionfly.


Photo © Tony Gunton