Controlling flies on the farm

The warm summer weather can mean an increase in the number of flies on pig units. Novartis Animal Health’s pig & poultry manager, Lydia Parkin, looks at the problems flies can cause, and how these flying pests can be tackled.

Flies aren’t just a nuisance, they carry diseases that can pose a serious health hazard to people and animals, and cause pig, poultry and dairy production losses estimated globally in the millions of pounds. Infested livestock become harassed and feed intake is drastically reduced with a significant reduction in production and serious economic losses.
The Clean Neighbourhoods and Environment Act of 2005 gives local authorities the power to check business premises to investigate complaints of flies ‘being prejudicial to health or a nuisance’ and issuing an abatement notice where premises fail to comply. Local authorities are also concerned about fly infestations affecting local communities resulting from the transport and use of manure from farms.
Flies risk causing complaints from local residents followed by enforcement action from your local authority, and they can also spread over 100 different pathogens, such as salmonella spp. Effective fly control forms part of most farm assurance schemes, and this must be carried out by fully trained operatives. Without monitoring and effective fly control, producers don’t fulfil the minimum assurance criteria.
Some farmers continue to see flies as a natural part of everyday farm life and a problem that will never disappear. To a certain extent they’re right, but it’s a problem that can be controlled. We have known about flies, from a scientific perspective, for well over 100 years. Attitudes have changed in that time, but still have some way to go. Flies must be regarded as dirty insects that carry disease and, therefore, must be controlled.
The types of disease carried by flies include viruses such as avian flu, parasites like tapeworm and enteric diseases including E coli and salmonella, which are especially relevant to pig producers. Bacteria, viruses, protozoa and even worm eggs are passed on by flies in a number of different ways; they can be eaten by the fly and are therefore in its gut, but even without any sort of ingestion, bugs still stick to the outer hairs and feet of the fly. The fly then simply lands on another animal, or on the animal’s feed, to transfer the pathogen.

Effective control
In order to effectively control flies, the fly life cycle must be broken. Flies breed rapidly and in the ideal conditions (environment and temperature), found on most farms, staggering numbers can be born every minute. The entire cycle of the house fly (Musca domestica) can be completed within eight days in the warmer summer months.
The adult house flies lay their eggs in warm, moist places such as manure and slurry. Within about 12 hours, the eggs hatch into tiny white maggots, or larvae. The larvae then complete three growth stages within 5-10 days (at 20-30C), turning into pupae. This pupal stage lasts only 3-4 days, with adult flies emerging ready to start the whole process again. In typical UK conditions there can be up to 15 generations born in a year.
As only 15% of the total fly population are adult at any one time, killing adult flies alone will not control the problem effectively and using the same adulticide continuously will promote resistance. Eggs, maggots and pupae ensure the problem quickly returns.
Proper control is best achieved using an integrated approach, whereby both larvae and adult flies are killed. This approach also helps to avoid resistance problems. Using different classes of adulticides will minimise the risk of resistance build-up, but only an integrated approach will control your fly problem effectively.
The Anti-Fly Programme developed by Novartis Animal Health, combines products containing two different active ingredients. Neporex, a larvicide, breaks the life cycle at the larval stage, while Oxyfly is an adulticide which can be used in rotation to minimise resistance problems.
Neporex contains the highly specific insect growth regulator cyromazine. This unique chemical stops larvae (maggots) developing into flies, thus breaking the fly life cycle. It is 100% effective against multi-resistant fly strains and is harmless to beneficial insects, spiders and birds. There’s no environmental risk and the treatment intervals are relatively long.
Oxyfly, meanwhile, is a broad-spectrum insecticide based on the potent pyrethroid lambda-cyhalothrin. It can be used to control adult flies and other pests, including litter beetles, cockroaches and red mite.
Oxyfly works quickly, but also has residual activity for up to 12 weeks. It’s easy to use, economical and doesn’t have an odour or cause staining.

Putting integrated fly control into practice

  • Start fly control early in the season. For best results, use the integrated farm fly programme all year round.
  • Apply Neporex to stop the fly supply within breeding sites.
  • Simultaneously apply an adulticide to reduce the adult fly population.
  • Alternate adulticides, such as Oxyfly, with another adulticide containing a different active ingredient to reduce the risk of resistance.

Identifying and tackling fly problems

Fly problems on a pig unit are likely to be caused by flies breeding on outdoor muck heaps or slurry lagoons. They may also be found breeding on the surface of muck under slats, and around the edges of pens/sheds bedded with straw.
In pig housing, look for any flies (likely to be house flies) and note their resting sites (fly dirt on walls, ceilings and under creep lids). These sites are where an adulticide can be applied as a paint (out of the reach of animals), or boards with granular adulticide can be hung to give residual fly control for a month. If farrowing crates have lids on, then the undersides can be pasted and granules applied so they adhere to the paste (use gloved hand to firm the adulticide into paste). Ensure that sows and piglets are not able to reach the applied product.
A torch is useful to check the muck surface through the slats along with a stick to turn over the top 2-3 inches of manure to see fly maggots. Turn back the top 2-3 inches of straw round the edges of any straw-based system and, again, look for fly maggots. Possibly note any fly larvae (brown chrysalis) and record your findings on a farm fly record sheet.
Anywhere you see fly maggots is an area for Neporex solution to be applied. All fly breeding areas should be treated using either a watering can or a knapsack sprayer to apply the product to all muck surfaces.
You’ll find product usage rates on label, but as a pointer, work out the muck area for treatment and use Neporex at the rate of 250gm of product for every 10 square metres of manure area.
Where Neporex solution is used to treat manure under slats, and applied through a knapsack sprayer, each 1kg of product should be dissolved in 5-9 litres of warm water (warm water aids dissolving). For application to any straw-bedded area, including outdoor manure heaps, then the amount of water can be doubled as water is only the carrier for the active ingredient.

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