Naphthalene. It is divided into natural mothballs and synthetic mothballs, which have the characteristics of insect prevention, moth prevention and mildew prevention. Synthetic mothballs are organic compounds. Most of the camphor balls containing naphthalene are white, with pungent smell, and sink in water, while natural camphor balls have smooth surface, white crystals and fragrant smell, and float in water, which are used for insect prevention, moth prevention and mildew prevention. Mothballs are generally extracted from natural camphor trees or made from turpentine by chemical treatment to synthesize mothballs with camphor effect.