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SUMMER FLY CONTROL

The later summer months are often the time when livestock around the farm get
the least attention, but that’s not strictly true. Cattle at grass in July and August
will certainly be attracting the interest of the local fly population! In this month’s
livestock nutrition article, David Thornton from Rumenco discusses the
importance of effective fly control.

Flies and midges that affect livestock are not only a nuisance and irritation to the animal,
they can also transmit diseases. And with the emergence of bluetongue in recent years,
we have become only too aware of the potential threat from these air borne vectors.

As the weather warms up, there are two main groups of flies which cause problems for
cattle producers: flies which bite and feed on blood; and flies which feed on the
secretions from the eyes, nose, udder and the sweat on the animal’s coat and skin.

Within the two groups there are a number of different types of flies, some of which
transmit disease, and others which are just a plain nuisance, but still distract the cow
from feeding.
Control of all flies is important, but tackling those that transmit disease should be the top
priority. The face fly is one of the most prolific and prevalent species. Known to transmit
New Forest Eye disease, the face fly is active from late spring until early autumn and
has several breeding cycles each summer. Similar in appearance to the house fly, it
lays its eggs in fresh dung and adult flies emerge just seven to 20 days later.

The face fly tends to be more prevalent in the south and feeds on eye and udder
secretions, as well as sweat from the body. It does not have a powerful bite, but does
have minute teeth, which cause lesions in the eye. It also carries Moraxella bovis, the
organism which causes New Forest Eye.”

The head fly is also a nasty piece of work. Identified as the culprit that transmits
summer mastitis, the head fly only has one breeding cycle per year and adult flies can
emerge in large swarms. They are widespread in the UK, particularly in the north of the
country, and cause intense irritation to the animal when feeding en masse.

The head fly lays its eggs in soil, manure and a variety of decaying vegetable matter and
because they only have one breeding cycle, controlling them early in the season will
reap dividends later in the summer months.

Other fly species, whilst not necessarily transmitting serious diseases, still create
significant problems. Stable flies, for example, deliver a nasty bite and have three or
more breeding cycles a year causing them to be active well into December if the weather
stays mild. They particularly like buildings and can be a real problem in the milking
parlour if they find their way in on the cows.

Control of all these flies during the season, and other relevant species such as sweat
flies, horse flies, black flies, midges and the common clegg, really is vital. Eradication is
impossible, but effective control should be the aim of every farmer and will not only help
herd health this season, it will also reduce potential fly populations for next year.

Understanding how your own farm appeals to flies is an important step forward in better
fly control. In fact, knowing where and when flies are breeding and then taking action to
restrict the potential farm fly population is just as important as controlling flies on the
animals. Flies breed in dung and vegetable matter, and near water, so it is important to
ensure their proliferation opportunities are as limited as possible by eliminating breeding
hotspots around the farm – or keeping livestock well away from water – and good
hygiene.

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