There are many ways of using essential oils but do not use any of them directly on your skin--they are very potent. Don't use any on your cat -- you'd burn her. Essential oils are not for consumption and cats can still reach their ears to clean. Ways to use oils: You can burn essential oils, steam inhale them, use them in another oil (only 6 drops of essential oil for 3-4 tsp of another oil--like grapeseed, avocado, almond, etc.) for human massage and bathing. You can make room sprays with distilled water and a few drops of eucalyptus. The product Second Nature bug spray has oils in them but it's mostly water.
This is from the book "Illustrated Elements of Aromatherapy" by Clare Walters. It's just reference, so take everything with a grain of salt. Do your own research. Talk to your vet.
"Essential oils can be made into a home made spritzer or personal body spray or into a room spray if diluted with distilled or mineral water and an alcohol such as vodka."
(I would recommend the room spray, maybe, to keep mosquitos at bay--remember, it's no substitute for proper heartworm preventative for your cats and dogs!)
Oils to use as insecticides: atlast cedarwood, bergamot, blue gum eucalyptus, cypress, geranium, lavender, lemon, lemongrass, rosewood, sweet basil, vetiver.
Basic recipe for a room spray (never to be used on skin):
1 tsp (5 ml) vodka
10 drops in total of one or two of the above essential oils
4 fl oz (100 ml) distilled water or filtered water.
Place the vodka and essential oils in a glass container with a lid and shake well. Top up the container with the water and shake again.
Hope this helps.
Hard work keeps fleas at bay. Keep at it!
-- Unknown