Combating Flies in Farming
The arrival of warm days and heat is often accompanied by the proliferation of flies in livestock farming. There are several ways to fight against flies[1] :
- Physical control methods
- Natural products
- biological control agents
Prevention
The cleanliness of livestock buildings is one of the main levers in the fight against the proliferation of flies. The favorable conditions for fly development are areas not trampled by animals, moist and warm.
Thus, manure, the floating solid parts of slurry pits, and decomposing materials constitute favorable environments.
Here are some reminders :
- Limit or even eliminate manure stocks : field storage of the last stocks, if possible, more than 500 m from residential houses, livestock buildings, and grazing areas.
- In the case of slurry pits under cow living areas, stir regularly to destroy larval development sites.
- Ensure that buildings and their surroundings are clean, dry, without stagnant water (silo tires, tarps…) and that the bedding is as dry as possible.
- Check the cleanliness of drinking troughs and feeding troughs.
- Avoid leaving milk residues first in the dairy and near the calf feeding area.
- Dust in particular the ventilation systems in buildings, to dry the environment.
Note : Composting manure is a very interesting technique in the fight against flies because it destroys almost all larvae thanks to the temperature rise.
Traps
Traps are an effective way to reduce the number of adult flies, especially inside buildings.
Different types of traps exist :
- Sticky traps (roll, sheet or ribbon).
- Baited traps (scented traps).
- Electric insect killers, to be used with caution due to the risk of spreading pathogens present on the fly’s exoskeleton when it disintegrates (do not use near milking areas).
Although fairly effective, the disadvantage of these traps is their non-selectivity.
Natural products
Essential oils
Certain essential oils applied to bedding and animals can be effective in repelling flies or interrupting the fly cycle.
- Method 1 :
- Put the essential oil in a shampoo cap (the shampoo helps disperse the oil in water)
- Then mix the cap in 5 liters of water, to be used within 3 to 5 minutes.
- Method 2:
- Mix the essential oil(s) at 10% in Cade oil.
- Spray inside buildings.
Not all essential oils are effective in the fight against flies :
| ESSENTIAL OIL | % EFFECTIVENESS |
|---|---|
| Basil | 88% |
| Tea Tree | 73% |
| Lemongrass | 58% |
| Geranium | 38% |
| Eucalyptus | 36% |
| Moringa | 20% |
| Lavender | 5% |
However, it should be noted that :
- The effect is more repellent than insecticidal.
- The effectiveness of essential oils is very variable depending on the stage : 50% on maggots and adult flies, 10% on pupae – requires direct contact for an insecticidal effect.
- There is little or no residual effect.
Warning, natural does not mean harmless!
It is preferable not to diffuse essential oils in buildings near the cheese dairy and during milking to avoid contaminating the milk : the smell and possibly the taste in processed products could be altered.
Other products, such as diatomaceous earth, lime, or various plant-derived products like coconut shell or peanut bran, can be added to bedding and contribute to reducing the number of flies.
Spraying diluted alcohol vinegar on the legs or under the belly of animals, before milking for example, is a simple and effective trick.
Biological control
The goal of biological control is to find a balance between different populations of insects to reach acceptable pressure levels.
Different auxiliaries can be used :
- Ophyra aenescens : predatory fly whose larvae feed on domestic fly larvae.
- Advantage : Ophyra flies do not go on animals
- Release every 15 days or once a month depending on pressure
- Macrocheles robustulus: predatory mite targeting eggs and young larval stages of the fly. It is less effective in dry environments.
- Muscidifurax raptorellus and Spalangia cameroni are parasitic wasps naturally present near stables. They lay their eggs inside fly pupae where an adult wasp will emerge instead of a fly. They are not as prolific as flies and have a slower development rate.
To be effective as biological control agents, natural populations must be reinforced by frequent releases of large numbers of individuals. These predators can reduce fly populations by up to 50%.
Implementation
To be effective, the use of parasitic wasps against flies must be done under several conditions :
- Start early in the season (March-April or even February if there was high pressure the previous year), before flies appear. Continue until mid-September or until the end of the fly season. Treatments must be renewed at regular intervals to act on all stages of insect development.
- Make a release on the same day as cleaning or after renewing the bedding within the next 2 or 3 days. Count at least one release per month, especially in spring and early summer. One release every three months is rather reserved for buildings less sensitive to flies. A release every 15 days is recommended for areas with high pressure.
- Adjust doses to be applied according to fly pressure. To do this, use sticky boards placed in sensitive areas. Plan at least 4 traps per building.
- Disperse parasitized pupae around known fly breeding areas or make a hole about 1 cm in the soil or manure, place a handful of pupae, cover with straw, soil, or manure to protect from wind, rodents, and birds.
The optimal storage conditions for micro-wasps are 10 to 15°C, in darkness for 1 to 2 days before spreading in the building.
- ↑ Chamber of Agriculture Bourgogne Franche Comté, What solutions to limit the proliferation of flies?
