How effective is naphthalene or moth ball as  repellent?« Back to Questions List

Naphthalene, a white solid toxic chemical with a strong smell, is often used as a moth repellent. It is the main ingredient of moth balls, small balls used as pesticides and deodorant. They are widely used for storing cloths or articles susceptible to attack by moths. 

Naphthalene, moth ball, moth, repellent, pesticide, sublimation, odor, insects, toxicity

Naphthalene possesses the characteristic of sublimation. When a substance becomes gas directly from solid state, it undergoes sublimation.  The gas generated from moth balls is toxic to moths and moths larvae.  The odor is unpleasant enough to keep moths and similar insects away from moth balls. Further, it is believed that when naphthalene gas is inhaled, other chemicals are produced in the body that damage cells and tissues. 

Naphthalene or moth balls have often been advertised as repellant to drive away mice, snakes, squirrels and other rodents. As per instructions, mothballs are to be used only inside tightly sealed containers. They are not expected to be used in open areas where the vapors can be inhaled by people. The gases released by mothballs causes irritation to moths thereby driving them away. Studies reveal that naphthalene is good repellant when used at 100% concentration in a highly closed area. But most repellants contain less than 10% naphthalene only. They become ineffective when used in open. Hence contrary to the advertisements, mothball is found to be an ineffective repellent as far as snakes, mice etc are considered. 

For human beings, naphthalene has low toxicity.  But many are highly sensitive to the smell. Inhaling the smell should be avoided as naphthalene is a pesticide. What are the uses of naphthalene?

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