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The horseflies are the most startling of these
insects, the largest being sturdy flies of some
20 mm in length. These larger species are not
common in Essex. However, several species
should be familiar to walkers in the Essex
countryside. They belong to the two genera
Chrysops and Haematopota. Their flight is
silent and the first you will know of the
arrival is the sensation of the bite on an
exposed portion of skin, usually the arms or
neck.
This insect will be a female, as the males of
horseflies, in common with mosquitoes and
midges, do not take blood. In fact, they lead
a rather blameless life, feeding (if at all) on
flowers. In these three families it is only
the female that takes a blood meal, which
provides a high protein diet that is needed for
the maturation of her eggs and her consequent
success in breeding.
Horseflies usually lay their eggs in batches in
rushes over water or wet mud and occasionally
in soil. The larvae are voracious predators
attacking and devouring other small
invertebrates.
Although the horseflies or clegs, as they are
often known, can at times be a nuisance, they
are not known to carry any disease in Britain,
though accidental infection of the bite wound
can lead to irritation and inflammation.
The next most prominent group is the Culicidae,
the mosquitoes, and these insects are far from
harmless. All female mosquitoes are
bloodsuckers though not all species attack