Animal Health Focus even more flies. Worst case scenario they can cause damage to the eye tissue of affected animals. They have been linked to the transmission of Moraxella bovis the bacteria responsible for ‘pink eye’. Head flies JULY 2018 www.irishfarmersmonthly.com Areas of manure/straw/decaying matter should not be allowed to accumulate as these areas provide the perfect environment for flies to breed. Surprisingly, the heat of fermentation in a dung heap will kill the developing stages of flies. In addition insecticides applied to the surface of manure heaps may prove beneficial. Pasture management Like face flies these are non-biting flies yet resemble house flies (biting) in appearance. They are often present in large swarms. They are attracted to the mouth, nose, ears, eyes and wounds of animals and man. Adults are most active from early June until late September and are common in close proximity to woodlands. Due to the intense irritation and annoyance, their presence can result in self-inflicted wounds (from scratching), which then attract more flies! On-going infection of such wounds is common and this may encourage blowfly strike. In cattle large numbers of head flies have been found in the udder region and the bacteria involved in “summer mastitis” has been isolated from these flies. This is strong evidence to suggest head flies are involved in transmission of this form of mastitis. Like face flies they also pose a risk for ‘pink eye’. Warble flies Reduction in the use of fields bordering woodlands has been advised in the peak risk period (June-September) where possible in the control of head flies. Affected animals may need to be housed and treated. Animal options Also known as cattle grubs, bot flies or gad flies; this type of fly is rare in Ireland. However it is important to recognise the condition as the risk of infestation still exists with importation of animals. Infestation is associated with the larval (immature) stage which overwinters in the animal and then appears as lumps on the hide the following May-June. The lumps are soft and painful when touched. Within 30 days the larvae emerge from the hide and drop to the ground before developing into adults. These adult flies are then responsible for infecting cattle which will show lesions next year. The warble flies cause issues not only for animal health and welfare but also with subsequent carcase and hide damage. Adult warble flies have a hairy appearance and yellow coloured bellies. They reach the size of an average bee. Warble flies cause cattle to “gad” – charge around in a wild state of fear which can lead to injury. Suspected warble fly infestations should be reported immediately to the Department of Agriculture, Food and the Marine. Blowflies Pour-on and spray preparations together with insecticide impregnated ear tags are widely used to reduce fly annoyance. For head flies a number of repellent creams are available for application around the base of the horns however many of these only prevent skin contact. In other words they do not reduce the annoyance caused by flies. Pour-on products applied at the dosing intervals recommended by the manufacturer will also aid control. It is best practice to start fly control early in the season (to reduce build-up of the fly population). There are many products on the market and it is most advisable to read the guidelines supplied by the manufacturers and adhere to exact instructions regarding administration, dose, frequency of use and withdrawal periods. Butox pour-on This product contains deltamethrin a synthetic pyrethroid. In cattle it is indicated for the treatment and prevention of flies and lice. It is advised to pour the dose along the animal’s spine from the base of the head to the tail . The person applying should wear gloves. It is safe to use during pregnancy and lactation. Butox PO has 18-day meat and 12-hour milk withdrawal periods for cattle. The time to apply this product is after evening milking and ensure that the full withdrawal period is respected. For fly control a single application provides protection for 8 to 10 weeks (depending on the degree of infestation, fly species and weather conditions) at which time treatment should be repeated. Butox in cattle Indications Flies: Prevention & treatment of flies on calves and other cattle Lice: Prevention & treatment of biting & sucking lice on calves and adult cattle Dose rate - Up to 100kg: 10ml - 100kg to 300kg: 20ml - Over 300kg: 30ml 10ml per animal irrespective of weight Mostly associated with fly strike in sheep, cattle can succumb to infestation too. Large populations of these adult flies are associated with poor management and lack of hygiene. Larval (immature) stages are often associated with infected wounds or with matted faecal stained hair coat. These flies do not feed on blood; instead their annoyance is caused by the movement on and off the animal. The flies are described as “vomit drop” feeders and fly from dungs and food to animals and spread bacteria on their feet and in their vomit. Treatment and control 38 Removing or at least reducing the source of infection Indoor environment is the most useful approach in controlling stable flies. In summary, the annoyance caused to cattle by flies is a real issue which has implications for both animal health and welfare. Remember to start fly control treatment in time this summer.