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Flying Insects (midges) in
Cardiff
Bay
What
are the flying insects and why are they here?
The flying insects are scientifically known
as Chironomids. Experts have advised they are non-biting because
they do not possess functional jaws.
These insects are known to rapidly colonise and dominate new
freshwater habitats.
As a more diverse ecology develops in the Bay the number of
insects will be kept in check through competition by predators,
such as birds, bats and fish. Although there has been a decline
in the emergence of these insects in
recent years, Cardiff Harbour Authority is
continuing to work towards reducing the number of these insects
in the Bay.
Adult
midges are often found flying in swarms near the water’s edge,
where they gather to mate. The females lay their eggs at the
edge of freshwaters where they hatch into larvae. The
larvae look like worms and are sometimes called 'Bloodworms' due
to their bright red colour. They live and grow
in silts on the bottom of the waterbody and in warm weather, the
larvae pupate and emerge from the water as adults and the cycle
starts again.
The
adult midges only live for a few days.
As
the ecology of the Bay develops, with fish and bird numbers
increasing, the midge numbers will be reduced by predation.
How
is
the Harbour Authority assisting
the achievement
of a balanced ecology?
The
Harbour Authority is continuing to work closely with a number of
experts to find an effective method to
control
the flying insects.
Initiatives
undertaken include:
Aquatic
planting has been carried out along the Bay edge to provide
ideal habitats and breeding areas for
coarse
fish. Surveys undertaken indicate that the coarse fish
population is developing well, and the fish
present are now of a size where they will be eating large
numbers of midge larvae.
Certain bird and bat species are excellent predators of adult
insects. For example, House Martins and
Swifts
which are excellent predators of these insects – House Martins
can eat up to 3,000 adult flies a day
and
swifts can eat up to 40,000 daily. Cardiff Harbour Authority has
encouraged the proliferation of these
species
by installing bird and bat boxes around the Bay and encouraging
developers to incorporate
conservation
schemes into construction projects.
A large scale experiment using a naturally occurring
larvicide has been completed under licence from the Health and
Safety Executive (HSE).
The larvicide works by eliminating the
insects in the larval stage before they hatch. Data obtained has
been analysed by experts at
Cardiff
University
, and initial results indicate the larvicide is an effective
control measure. Cardiff Harbour Authority has therefore applied
to the HSE for a licence to use the larvicide throughout the
Bay.
The
Harbour Authority is continuing to work closely with scientists
at
Cardiff
University
and the
National
Museum
and Galleries of Wales. The intensive monitoring of insect
larvae numbers in the silt of the Bay is continuing in order to
determine areas of highest concentration to assist in
application of control measures.
Also, in addition to monitoring the
migratory salmon and sea trout, both sonar and netting surveys
of coarse fish in the Bay and rivers will continue to be
undertaken. A Conservation Strategy has been developed for
Cardiff
Bay
, and this will further enhance the ecological development of
the area.
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