Mothballs are small, white, solid chemical pesticides used for protecting stored items from damage caused by clothes moth larvae. They are recognizable by their strong, pungent odor, which results from the active ingredients slowly turning into a gas. This chemical release creates a toxic environment that kills the fabric-eating pests.
Primary Use: Protecting Stored Fabrics
The legally approved use for mothballs is to control clothes moth larvae, which eat holes in natural fibers like wool, silk, and cashmere. Mothballs eliminate the destructive larvae and eggs, as they are not designed to repel or kill adult moths. For the product to be effective, the toxic vapor must be contained and concentrated.
Mothballs must be placed with garments inside an airtight container, such as a sealed trunk, plastic storage bin, or tightly closed garment bag. Using them in an open closet or drawer allows fumes to escape, rendering the pesticide ineffective and exposing people and pets to the chemicals. Product instructions specify the exact volume of space the mothballs are intended to treat, emphasizing the need for a sealed environment.
The Science of Sublimation: How Mothballs Work
Mothballs contain high concentrations of one of two active ingredients: naphthalene or paradichlorobenzene (PDB). Both chemicals are solid at room temperature but share a unique property known as sublimation. Sublimation is the process where a solid substance transitions directly into a gas or vapor without first becoming a liquid.
As the solid mothball slowly sublimates, it releases a toxic vapor into the sealed storage container. This concentrated gas kills the clothes moth larvae and eggs, preventing damage to stored fabrics. The strong, sickly-sweet odor associated with mothballs is the smell of this pesticide vapor, which is continuously released until the solid ball completely disappears.
Safety Concerns and Misuse
Despite their intended use, mothballs pose health risks, especially when used improperly. The toxic fumes can cause short-term symptoms like headaches, nausea, and eye or throat irritation if inhaled in unventilated areas. Long-term exposure to these vapors has been linked to serious health issues, including damage to the liver and kidneys.
A concern is the risk of accidental poisoning, particularly among children and pets who may mistake the small, white balls for candy or treats. Ingesting mothballs can lead to severe symptoms, including abdominal pain and discolored urine. Because of these dangers, the Environmental Protection Agency (EPA) strictly regulates their use.
The most common misuse of mothballs is attempting to use them as a general repellent for pests other than clothes moths, such as mice, snakes, squirrels, or insects in gardens. Using mothballs outdoors or in any location not specified on the product label is a violation of federal law. This practice is dangerous because the chemicals contaminate soil and water, harm wildlife, and expose the surrounding environment to toxic fumes.
Safer Alternatives for Fabric Protection
Given the toxicity and strict usage requirements, many people seek safer, non-chemical methods to protect stored clothing. Aromatic cedar is a popular alternative, as the wood’s natural oils act as a repellent to moths, though it does not kill them. Cedar blocks or chips should be refreshed periodically to maintain their scent and effectiveness.
Other natural repellents include sachets filled with dried herbs like lavender, rosemary, or cloves, which emit scents that moths find unpleasant. For maximum protection, garments should be cleaned thoroughly before storage, as moths are attracted to residual human scents and stains. Storing items in airtight, vacuum-sealed bags or plastic containers provides a physical barrier that prevents pests from accessing the fabrics entirely.