Can Lavender Oil Kill Parasites?

Lavender Essential Oil

• The essential oil of lavender is derived from the flowers of lavender (Lavandula spp.), which can grow outdoors in U.S. Department of Agriculture plant hardiness zones 4 through 11, depending on the species. Lavender essential oil is usually made through steam distillation of lavender flowers or by mechanically pressing them to extract the concentrated essences and aroma of the plant matter, according to the National Cancer Institute. It takes up to 200 times the amount of flowers to make a small amount of lavender oil. The resulting oil contains high concentrations of terpenes, phenols, alcohols and aldehydes, according to ScienceDaily. Lavender essential oil is most commonly used in aromatherapy.

Insects Deterred by Lavender Oil

• A study of the effects of essential oils, including lavender oil, on garden pests, published in the August 2009 issue of the "Journal of Economic Entemology," revealed that bug spray formulas containing lavender oil eliminated citrus mealybugs. Another study, published in the January 2010 issue of "Munis Entomology & Zoology" found that lavender essential oil eliminated cowpea weevil (Callosobruchus maculatus F.). Lavender oil helps deter mosquitoes and ticks, according to "Biopesticides International." These sources also reported that lavender oil used to eradicate these pests left little potentially harmful residue behind.

Insecticide and Herbicide

• While lavender essential oil is generally safe for use around people and pets, it can harm your plants. The same active chemicals in lavender essential oils that have insecticidal properties also have some herbicidal properties. A 2009 study published in the "International Journal of Environment and Health" found that lavender essential oil helped to kill weeds when applied to their roots, according to ScienceDaily. Fortunately, the oil didn't stay in the soil very long, thus it didn't contaminate it against future growth. To avoid harming your plants, don't apply lavender oil in its undiluted state.

Lavender Oil in the Garden

• To help deter parasites without harming your plants, spritz them with a mixture of 4 to 8 drops of lavender essential oil per gallon of water, recommends "The Complete Book of Essential Oils and Aromatherapy." Apply in the evening when sun damage is least likely to occur. This spray may also clear mildew and fungi from your plants. If you'd rather not put any lavender oil on your plants, apply to cotton balls, a few drops on each, and place these around the garden to deter pests. However, essential oils evaporate quickly so you may need to replace daily. And however used, lavender oil won't get rid of all your garden parasites, so you may need to use plant-safe insecticides to deter others.