Mothballs, moth flakes, crystals and bars are insecticides. They come in a solid form that slowly gives off a toxic gas that kills moths and other insects. Mothballs in the U.S. contain very high concentrations of either naphthalene or paradichlorobenzene as active ingredients. They are meant to be used in closed, airtight containers so that the fumes they produce are trapped. The trapped fumes build up and kill any clothes moths inside. If mothballs are used out in the open, they can harm people, pets, or wildlife that may touch or eat the mothballs, or breathe their vapors.
If you have questions about this, or any pesticide-related topic, please call NPIC at 1-800-858-7378 (8:00am - 12:00pm PST), or email at firstname.lastname@example.org.