To most people flies are “just flies and a nuisance” but animal health SQPs at the meeting organised by Agrihealth got quite a shock when Aurelie Moralis, veterinary consultant with Zoetis, outlined the large variety of flies found on farm and the effect they can have on production losses and transmission of disease.
Aurelie said: “Nuisance flies’ mouth parts are adapted for sponging and scavenging and they feed on sweat, skin secretions, teats, saliva, urine and faeces. Several species also act as vectors for a range of pathogens.”
Outlining the range of nuisance flies, Aurelie mentioned the face flies which transmit Pink Eye; head flies which transmit summer mastitis in cattle and cause black cap or broken head in horned sheep.
Biting flies have piercing mouth parts that bite and feed on blood – these include stable flies, horn flies, midges and mosquitoes. Biting flies cause intense irritation and can be vectors for disease transmission. Midges, for example, transmit viral diseases including Bluetongue virus and Schmallenberg virus. Stable flies, horn flies, horse flies and clegs all cause irritation and painful bites and some are responsible for blood loss and transmission of disease.
Myiasis flies such as blowflies lay their eggs on wounds and the maggots feed on host tissue.
Fly numbers are determined by environmental factors such as temperature, humidity, breeding habitat, reproduction capacity and availability of hosts on which to feed. Environmental management can play a role i.e. the management of manure heaps, slurry lagoons ventilation, bedding and effluent drainage.
Economic losses are suffered due to hair or wool loss, skin damage, poor performance, weight loss, reduced production and increased treatment costs. There are also indirect costs from disease transmission.
Treatment of flies includes:
Fly & Lice Spot On™ – a 1% topical deltamethrin application which provides up to eight weeks protection with activity against midges for up to five weeks. It is an effective fly killer – not a fly repellent.
Flectron ® Fly Tags are resin impregnated ear tags containing cypermethrin which provide season long protection for flies on cattle.
Dysect™ Sheep 12.5 g/l Pour-On is licensed for treatment and prevention of blowfly strike as well as lice and ticks in sheep. Dysect™ Cattle 15g/l Pour-On will provide fly and lice control in cattle for up to eight weeks.
Insect growth regulators (IGRs) are used in the prevention of blowfly strike in sheep as they act on the maggot stage and should be used before periods of anticipated challenge.
Pour-On and Spot-On treatments are simple, low labour, stress free methods of application, applied on the back or on one spot in the middle of the back. The drug diffuses into the lipid layer of the wool and/or skin and spreads across the body.
Aurelie’s advice is to start early – treat as soon as flies begin to emerge.
To determine this Zoetis have set up #parasitewatch on Twitter (@sheep_farmers) and Facebook (Sheep Farmers) whereby a number of farmers around the UK are using fly traps and reporting when the flies begin to arrive in large numbers. Farmers can also see how to make these simple fly traps on the #parasitewatch page of Twitter in order to determine the fly population in their own area.