Organic Fly Repellent with Essential Oils
Tired of fly sprays and the unwanted chemicals they contain? There is a very easy solution to keeping flies away from the outdoor dining area and you can do it yourself.
Clean out a small tin with a lid.
Take a clean piece of cloth or a small piece of dish sponge able to fit into the container. Saturate it with one of the following oils (after it has been diluted appropriately, see Tips):
Lavender oil – lavender is considered to be particularly effective against flies
Citronella oil (dilute with water first)
Eucalyptus oil (dilute with water first)
Pennyroyal oil (dilute with water first)
Peppermint oil (dilute with water first; likely more effective against mosquitoes but also considered to work against horse-flies.
Lemongrass oil (dilute with water first)
Place the cloth in the tin and shut the lid. Allow to sit for 24 hours.
Use. Whenever you need to use the tin, remove the lid and place on the entertaining table. Make as many as you wish to put around the entertaining area to deter flies.
Replenish the oil after each use; once open to the air, the strength weakens and needs to be topped up
Wear gloves when handling the saturated cloth, especially if you are handling food and/or have skin sensitivities.
You can amplify the effect of the essential oils by using candles. Simply add a few drops of the chosen essential oil (or use different ones at different ends of the table) into the melted wax area of a burning candle. The odour will waft out as the candle burns.
If you are familiar with combining essential oils to produce scents, try a combination of the above suggested essential oils for a pleasant odour and possibly a more powerful fly dissuader.
Note that lavender oil can be used freely without needing to dilute with water. Water dilution should follow the instructions accompanying the essential oil. Providing you do not wear the oil, dilution at a ratio of 1 part oil to 3 parts water will likely prove sufficient for most oils but know the properties of your oils before making assumptions. If you intend to wear any of these oils as a repellent, the advice here does not apply and you should seek information from the appropriate source.
Always read the warnings accompanying essential oil products and do not use if you are pregnant, have a poor immune system or allergies unless you know the oil to be safe.
Always keep essential oils out of the reach of children. Many are toxic if ingested, especially pennyroyal. Containers should be kept out of reach.
As with any herbal remedy, you are the best judge of whether or not the herbal solutions are doing what you seek from them. If not, experiment with different types until something meets your needs. Sometimes the effectiveness of oils is dependent on local conditions.
Exposure to lavender and tea tree oils may lead to gynecomastia in prepubescent boys. 
Stuff You Need:
Small tin with lid; ideal tins include confectionery tins, cough drop tins, candle tins etc.
Small piece of cloth, for example, calico, cotton, handkerchief etc.; or cut a piece of dish sponge down to size.