The rinds of citrus fruit contain citrus oil.
Its sweet smell is harmless to people and pets but repels many insects. Because some plants are sensitive to citrus oil, be sure to test first.
2 lemons and 1 litre water
Grate the lemon rind and put aside. Bring water to the boil. Add the rind to the water and remove pan from heat. Cover and let stand for 24 hours.
Strain into a clean spray container.