Why should I add TerraShield essential oil blend to my collection? TerraShield blend is formulated with a unique combination of essential oils known for their rich content of citronellol, such as Citronella and Geranium, and refreshing scents, such as Cedarwood and Peppermint. Before heading outside, apply TerraShield to your arms, legs, and neck or diffuse on your patio for an elevated outdoor experience.