Nootkatone is a natural organic compound and is the most important and expensive aromatic of grapefruit.It is a sesquiterpene and a ketone. Nootkatone was previously thought to be one of the main chemical components of the smell and flavour of grapefruits. In its solid form it is usually found as crystals. As a liquid, it is viscous and yellow. Nootkatone is typically extracted from grapefruit, but can also be manufactured with genetically modified organisms, or through the chemical or biochemical oxidation of valencene. Nootkatone in spray form has been shown as an effective repellent/insecticide against deer ticks] and lone star ticks. It is also an effective repellent/insecticide against mosquitos, and may repel bed bugs, head lice and other insects. It is environmentally friendly insecticide, because it is a volatile essential oil that does not persist in the environment.