Flies in the stall
Stall flies are divided into stinging and non-stinging flies. The stable fly is a typical example of a stinging fly (found in cattle and pigs) that feeds on the blood of larger hosts. Non-stinging flies – such as the housefly – also rely on proximity to larger livestock (found in cattle, pigs, chickens), because they feed on animal secretions, which they find in wounds and natural body orifices.
In only one egg deposit, a female fly can lay up to 1,000 eggs. In stalls, they prefer to lay these in animal excrement or in the floating layer of liquid-manure. In this way they can produce six to nine generations of new flies per year. As a rule, the larvae hatch from the eggs after about eight days and pupate after another six days until they finally become flies. A warm and humid environment is ideal for this development. Flies usually live for about 14 to 18 days.
Stall hygiene is what counts!
Good stall hygiene is incredibly important for livestock health. This should include extensive basic cleaning in the spring (mid-April to early May). This helps to reduce fly breeding and to contain the spread of stall flies.
Regular hygiene measures in the stall:
- Good ventilation as stall flies don’t like drafts. Caution: livestock should not be exposed to draughts.
- Carefully clean hard-to-reach corners and niches
- Remove feed, manure and milk residues
- Avoid water leaks and feed contamination
- Aerate, stir and drain slurry
- Empty slurry channels as completely as possible
- Remove floating layers on the slurry
- Muck out regularly and carefully
- Aerate and rearrange the solid manure
- Keep the feed station clean
- Prevent infections between stalls/stall areas/partitions
Hygiene should also be observed in outdoor areas to prevent potential breeding sites. Entrances, such as open doors, should be kept closed as far as possible.
Around 80 percent of the insect population consists of larvae and pupae in breeding sites. Only 20 percent of the flies can be seen flying in the stable. Therefore, it is very important to find and remove the breeding sites in the stall and in the surrounding area.
These can be found anywhere warm and humid:
- under fences, grids and box partitions
- in calf pens
- in floating crusts on slurry and in slurry channels
- in deep litter areas and wet stalls
- in excrement
- on automatic feeders
- on and under slatted floors
Controlling the various stages of development is crucial for sustainable success. Starting preventive and control measures early on is particularly effective.
Ichneumon wasps and black dump flies for larvae control
If you want to control stall flies effectively, you can simply introduce their natural predators. This includes black dump flies and ichneumon wasps, which use stall fly larvae as food. The beneficial insects can be used in slurry channels or in deep litter and sloped floor areas – where stall flies prefer to have their breeding sites. There, these light-shy and slow-flying insects are effective in helping to stem the increase of the stall fly population. Both beneficial insects rarely leave their place of origin and therefore don’t bother the livestock in the stall.
A second option to take action against stall flies are so-called larvicides. These highly effective products are used against fly larvae in manure, slurry or bedding and stop their development. However, these cannot be used in conjunction with black dump flies and ichneumon wasps, as these also affect beneficial insects. Please note: to use larvicides effectively, you have to know the breeding sites of the pests. The effect is also very slow. Larvicides are not suitable for use against adult flies and pupae.
Fly control methods
Although adult flies only make up a small part of the total population, measures should be taken as soon as the first flies appear.
- Attach fly screens, UV light traps, adhesive traps or adhesive tapes
- Hang up fly bags with pheromone bait
- Use of adulticides. These are nerve poisons that are absorbed by flies in bait traps and food traps. Ensure that different groups of active substances are used, to prevent resistance from building up.
- Swallows help control stall flies, and should have free access to the stall.
Flies in the meadow
Flies in the meadow cause stress in cattle. The animals spend most of their time fending off pests, which reduces the positive effects of grazing. In the worst case scenario, milk production and live weight gain can decrease by up to a third. Black flies, biting midges and meadow flies are the most common fly species in the meadow. In order to keep the disadvantages of flies as low as possible, prevention measures are advisable at the same time.
Two systems are currently available for this. Both should be used in the spring to slow down the growth of an insect population.
Insecticide-impregnated ear tags
These soft plastic ear tags contain active ingredients from the pyrethroid group. They have a deterrent, and sometimes fatal, effect on ectoparasites. Depending on the manufacturer, the effect lasts four to five months. At the beginning of the grazing period, an ear tag is given to each animal and removed at the end of the grazing period, as the use is limited to the grazing period.
Two so-called formulations containing the active ingredient deltamethrin are available on the market. Deltamethrin is particularly effective against meadow flies and does not lose its strength even in the rain. The product is applied along the back bone of the animal from the base of the skull to the base of the tail and is effective for six to ten weeks. However, the active ingredient has a waiting period on edible tissue. Other products based on the active ingredient cyfluthrin are also available, but their effect is shorter, at four to six weeks.
Even with insecticide-impregnated ear tags and infusion processes, damp areas and excrement on the meadow should be avoided as far as possible, as these are ideal breeding grounds for flies. In addition, cattle should always have access to shady areas.
Flies are a high stress factor for the animals, in the stall and in the meadow. In addition, they transmit diseases and, therefore, pose an increased risk to health. To prevent higher economic losses, regular hygiene measures should be taken in the stall. It is particularly important to control flies at the larval stage, as this is the only way to successfully stop the population developing.
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