Fly spray!

My OH makes something like that, only, without the Surgical Spirit. It works as well as anything.

Make sure it's good strong tea, we use the dregs from the pot, so it's nice a black!
 
Ditto ^^^^^ surgical spirit isn't necessary. Go easy on tea tree oil if it is an essential oil. I only put about 20 drops in 6.5 litres of mix, same with the citronella.

I make tea with 8 tea bags and 1 litre of boiling water.
Cup of vinegar
Squirt of washing up liquid
20 drops of oils
Top up to 5 -6 litres with water
Spray or sponge on.
 
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