Tuesday 10 September 2013


In an effort to discourage insects I have tried burning citronella candles but the quality of wax is variable. Some expensive ones still smoke even when the wick is trimmed every hour or so.   Googling to find an alternative, there has been  academic research on the subject and this is the basic result:

- reed diffusers are many times more effective than candles
- the smell which best deters insects is not citronella but rose geranium (that is, a variant of geranium, not roses, although there is some resemblance in the perfume).

I do not want to spend a fortune on diffusers but I'm willing to punt a few pounds on avoiding mosquito bites.   I therefore obtained the following

- A packet of 8 reeds which were down to 50p
- a jam jar with a lid
- Odd oil which was no longer suitable for cooking - a lurking bottle of almond oil and a lonely splash of corn oil. Which ever it is, the oil should not have a strong smell if its own. Baby oil is OK, though.
- surgical spirit or other solvent such as vodka.
- a bottle of geranium oil and one of citronella as I do not like geranium on its own. 

Together the perfume oils should cost about £12 and you may be able to find them much cheaper. Any health store will have them.

Mix together the geranium oil, the citronella oil and the cooking oil. Exact quantities do not matter but two small bottles of essential oil will strongly scent at least half a pint of base oil.

Punch 8 holes in the lid of the jar (I used a pointy thing from the screwdriver case and hit it with a hammer)  such that the reeds can be inserted. You could put them straight in the jar but if it fell over the gunk would go everywhere.

Put half an inch of surgical spirit in the bottom of the jar, then top up with as much again of the scented oil.   The oil does not dissolve perfectly in the spirit but they stir together well enough to soak up the reeds.   Some people use vodka instead of surgical spirit which would work but is not as cheap.  On the other hand, at least it doesn't smell of surgical spirit.

Put the lid on the jar, insert the reeds, give it a gentle swirl to encourage the oil and spirit to mix up again, and wait.  Reverse the reeds after a few hours to start the diffusion properly.  You will know it is working because the place will smell like hospital flowers but it is not a bad smell - just peculiar.  You  would not want to dab it behind your ears.  Indeed, you must label the rest of the oil carefully to make sure it does not get confused with cooking oil.

An inch of the mixture in the jar will last at least a month which is bad news if you hate the smell but I can confirm that it has dissuaded all but the most determined bluebottle from coming in.  There is enough oil to top up the diffuser for about a year, meaning the cost of a home-made insect repellent is a little over £1 per shot maximum compared to £10 commercially.  Give the jar a swirl every now and then to re-mix the solvent and oil.

After about two days the stronger smells go and the remaining level is not noticeable to humans - just a lemony background note - but the insects seem to stay away. 

It is worth sticking the jar inside a prettier container - say, a plant pot or jug  - because otherwise it looks like you've gone all Howard Hughes and are displaying your own urine samples.


lilith said...

Fantastic WOAR, this is so helpful. I wondered how I could make my own reed diffuser as they seem to cost a fortune for a reasonable fragrance. Elby's cousin does these and they are lovely but don't last a year. The grapefruit and green tea is particularly delicious.

JuliaM said...

Lavender is also supposed to be good at keeping away insects, and there's cedarwood for moths (though you have to keep sanding it to keep the smell fresh).

lilith said...

Lavender oil attracts bees, as someone who plastered their dog with it found out to the pooches cost! (no, not us!) We have it in the kitchen for burns...stick it straight on and later wonder where the blister would have been. Magic :-)

Uncle Badger said...

This is fascinating, WOAR, thank you.

I live in a mosquito infested area and react badly to bites - so much so that I have one of those Boots plug-in insecticide dispersers running for about two months every year, when the brutes are in search of what they clearly consider to be manna from heaven (otherwise known as badger blood).

I'm not happy sleeping in a cloud of insecticide but the alternative is walking around covered in itchy lumps the size of small grapefruit.

I shall experiment!

Woman on a Raft said...

The only other thing I noticed which seemed to make a difference was salt. That is, if i went completely in the sea and did not wash it off, then the mosquitoes either could not smell me or or the salt deterred them or perhaps the salt changes the reaction at the skin.

It is possible that salt water in a bath would do the same. I don't think it has to be fancy salt but it might be worth trying Dead Sea Salts anyway as it is widely available.

It might just be that diffusers act as 'jungles' creating an odour background which confuses the insects and making it more difficult to find the fragrance of a juicy ankle.

Let us know how your experiment goes Uncle Badger. I think if I was in a seriously risky area I'd probably be using a lot of Deet on soaked ankle and wrist bands as that is still better than bites going septic or increasingly allergic reactions.