mothballs are small balls of chemical pesticide and deodorant.they are used when clothing and other articles susceptible to damage from mold or moth larvae are stored. older mothballs were made primarily of naphthalene. because naphthalene can catch fire easily, modern mothballs use 1,4-dichlorobenzene instead. both of these ingredients have a strong, pungent smell often associated strongly with mothballs. camphor, an insect repellent, can also be used in mothballs.