Eucalyptus is a pleasant smelling herb to most people, but fleas have a different opinion. The essential oils from eucalyptus and other herbs can be combined to make a natural flea collar for your pet to get rid of fleas. Combine eucalyptus oil, sage and citronella and dip a piece of string or thin rope in the mixture to saturate it then tie it around your pet's neck to get rid of the pests.
Orange oil is an herbal product you can use to kill fleas once they have set up shop on your pet. Add 1/2 tsp of orange oil to any regular shampoo and mix it together and scrub your pet thoroughly. Always start at the neck and work your way down so the fleas don't rush to the animal's face. You'll want to vacuum the house after the wash and throw away the vacuum bag immediately to prevent repopulation, according to the Giving Herbs to Your Pet for Dummies website.
Pennyroyal is a potent flea repellent and killer. This herb is best used to plant around the perimeter of an area you wish to keep fleas away from. Using the herb topically or taking it internally is not recommended because of specific health hazards. According to The Daily Puppy website, pennyroyal can cause liver damage and neurological problems.
Neem oil is a safe and effective flea killer that will rid cats and dogs of the pests with a topical application. This herbal oil from India is easily found in pet stores or you can grow the plant indoors if you choose to get it directly from the source.
According to The Daily Puppy website, neem oil is likely to cause a total eradication of fleas on your pets.