Orange oil is an essential oil produced by glands inside the rind of an orange fruit. It is extracted or steam distilled as a by-product of orange juice production. It is composed mostly of d-limonene, and is therefore often used in place of pure lemon, which can be further extracted from the oil by distillation.
Limonene is what gives citrus fruit their familiar aroma, and is therefore used in perfume and household cleaners for its fragrance. It is also an effective, environmentally friendly, and relatively safe solvent, which makes it an active ingredient of choice in many applications, such as, but not limited to, adhesive and stain removers, cleaners of various sorts, and strippers.
The limonene which is the main component of the oil is a mild hand irritant, by virtue of dissolving the protective oils in the skin. It is wise to wear solvent-resistant gloves when handling limonene solutions.
Limonene has been observed to cause cancer in male rats, by reacting with α2U-globulin, which is not produced by female rats. There is no evidence for carcinogenicity or genotoxicity in humans. The IARC classifies d-limonene under Class 3: not classifiable as to its carcinogenicity to humans. 
For more details of the regulatory status and toxicity, see limonene.
d-Limonene serves as a natural insect repellent for citrus fruits. Direct contact with d-Limonene can act as an organic insecticide. Experiments with fruit flies have shown that they by-pass this problem by laying eggs between the oil-producing glands. Also effective on Drywood Termites