Do Mothballs Keep Mice Away?

Mothballs have long been used as a popular method to repel pests such as moths, ants, and even mice. However, while some people claim success in keeping mice away with mothballs, there is limited scientific evidence to support these claims.

Mothballs contain a pesticide called naphthalene or paradichlorobenzene, which releases a strong odor that can be irritating to pests. The odor is said to deter mice by overwhelming their sensitive sense of smell, driving them away from the treated area. However, mice are highly adaptable creatures and can quickly become accustomed to strong smells. This adaptation may render mothballs less effective over time.

Moreover, mothballs are intended for use in closed storage spaces and not for open areas where people or animals live. They contain toxic chemicals that can pose serious health risks if consumed or inhaled, especially in high concentrations. The use of mothballs in open areas is not recommended, as the risk of chemical exposure to humans and pets outweighs any potential benefits.

To effectively prevent mice infestations, it is best to focus on sealing entry points, removing potential food sources, and maintaining cleanliness. This includes sealing cracks and holes, keeping food stored in secure containers, and regularly cleaning up crumbs or spills. Using traps or electronic deterrents can also be more reliable and safer options for mouse control.

To sum up, while mothballs may have some effect in repelling mice initially, their long-term efficacy is questionable. It is important to prioritize safe and proven methods of rodent control to ensure the well-being of both humans and animals.


What are mothballs?

Mothballs are small balls or pellets of a chemical substance that is commonly used to repel and/or kill moths and other insects that tend to damage or infest clothing, fabrics, and household items. They have been widely used for over a century as a popular method to protect textiles from moth damage.

Composition of mothballs

The composition of mothballs typically consists of one or more volatile substances that release fumes or vapors that repel, suffocate, or poison insects. Historically, two main types of chemicals have been used in the production of mothballs: naphthalene and paradichlorobenzene (PDB). Naphthalene is a white crystalline solid derived from coal tar, while PDB is a white crystalline solid synthesized from benzene.

Naphthalene mothballs are made by compressing or molding naphthalene into small spherical shapes. When exposed to air, naphthalene sublimes from its solid state into a gas, which produces a characteristic odor that repels insects. The principle behind naphthalene’s effectiveness is that its vapor is toxic to many insects, including moth larvae. However, naphthalene is also toxic to humans and animals if ingested or inhaled in large quantities, and prolonged exposure can cause health issues.

The history of mothball use

In the mid-20th century, paradichlorobenzene became a popular alternative to naphthalene due to its lower toxicity and less pungent odor. PDB mothballs are made using a similar process, but the chemical properties of paradichlorobenzene differ from naphthalene. PDB slowly sublimes at room temperature, releasing a gas that repels insects. Although considered less toxic than naphthalene, PDB can still be harmful if ingested or inhaled in large amounts.

The use of mothballs has a long history dating back to ancient times. The ancient Egyptians used various substances, including herbs and spices, to protect their clothes from moths. The Greeks and Romans used aromatic plants, such as rosemary and lavender, for the same purpose. These early methods relied on the natural repellent properties of these plants rather than chemical compounds.

The modern-day concept of mothballs began to take shape in the 19th century with the discovery of the insecticidal properties of naphthalene. In the early 20th century, the commercial production of naphthalene mothballs became widespread, providing an efficient solution to moth infestations and damage. The use of PDB mothballs gained popularity in the mid-20th century due to its improved safety profile and milder odor compared to naphthalene.

Over time, concerns about the potential health and environmental risks associated with naphthalene and paradichlorobenzene have led to regulatory restrictions in some countries. In recent years, alternative moth repellents, such as cedarwood chips, lavender sachets, and essential oils, have emerged as more natural and environmentally friendly options.


How Do Mothballs Work?

Naphthalene is the traditional and most commonly used chemical in mothballs. It is a white crystalline substance that is derived from petroleum distillation. The strong smell of mothballs comes from the vaporization of naphthalene. When naphthalene is exposed to air, it sublimates, which means it transitions directly from a solid to a gas without passing through a liquid phase. This gas is what creates the pungent odor and helps repel moths and their larvae.

The vapor released by naphthalene works by interfering with the life cycle of moths. Mothballs slowly release a steady stream of gas into the air. When moths or their larvae come into contact with the gas, it disturbs their senses, making it difficult for them to detect essential signals such as food, mates, and suitable environments. As a result, they become disoriented and their normal functioning is disrupted, eventually leading to their death.

Paradichlorobenzene is an alternative chemical used in some mothballs. It functions similarly to naphthalene, but has a slightly less intense odor and sublimates at a slower rate. Instead of killing moths and their larvae, paradichlorobenzene works by repelling them. Moths are deterred by the odor and will avoid areas where mothballs are present.

To ensure effectiveness, mothballs must be used correctly. They should be placed in airtight containers or directly with stored items, ensuring that the gas emitted is concentrated enough to be effective. Additionally, proper ventilation is crucial to prevent an excessive buildup of the mothball odor. Mothballs should never be used on clothes that are regularly worn or stored in areas frequented by humans, as the chemicals can be harmful if ingested or inhaled in large amounts.

It is important to note that while mothballs are effective in repelling and killing moths and their larvae, they are typically used as a last resort due to their potential harmful effects. The chemicals used in mothballs can be toxic to humans and animals if ingested or inhaled in large quantities. They can cause symptoms such as headaches, nausea, dizziness, and respiratory issues. Therefore, it is recommended to use alternative, less toxic methods to protect against moths whenever possible.

In conclusion, mothballs work by releasing chemicals, usually naphthalene or paradichlorobenzene, in the form of gas that repels or kills moths and their larvae. The vaporized gases interfere with the moths’ sensory perception and disrupt their normal functioning, eventually leading to their demise. However, it is essential to use mothballs responsibly, following safety instructions and considering less toxic alternatives to protect both ourselves and the environment.

Effectiveness of mothballs in Repelling mice

Scientific studies and evidence

  • Laboratory experiments: Some lab studies have shown that the chemicals in mothballs can repel mice in controlled environments. However, results may vary depending on the concentration of the active ingredients and the duration of exposure.
  • Field studies and real-life application: There is limited scientific evidence to support the effectiveness of mothballs in repelling mice in real-world situations. Mice may be more resistant to the smell in larger, open spaces, and may find alternative routes to avoid the fumes.

Comparison with other rodent repellents

  1. Traditional traps and poisons: Mechanical traps and poisons are generally more effective in controlling mouse populations, but they can also be dangerous to humans and pets if not used properly.
  2. Ultrasonic devices and natural repellents: Ultrasonic devices emit high-frequency sounds that are supposed to deter rodents, but their effectiveness is debatable. Natural repellents like essential oils and spices may have some success in repelling mice, but may need to be applied frequently.

Risks and downsides of using mothballs for mice control

Health risks for humans and pets

Mothball fumes can be toxic to both humans and pets when inhaled or ingested.

Symptoms and health complications

  • Inhalation: Headaches, dizziness, nausea, eye and respiratory irritation, coughing, and difficulty breathing.
  • Ingestion: Abdominal pain, vomiting, diarrhea, fever, seizures, and potential damage to the liver and kidneys.

Environmental concerns

Mothballs can also have negative effects on the environment.

  1. Contamination of soil and water: Mothballs can leach into soil and groundwater, posing risks to aquatic life and other organisms.
  2. Impact on non-target wildlife: Mothball fumes can also harm beneficial insects, birds, and other wildlife that come into contact with them.

Legal restrictions and regulations

Using mothballs to repel mice may not be legal in some jurisdictions, as they are intended for moth control and not rodent control.

  1. Improper usage and potential penalties: Misusing mothballs can result in fines or other penalties, depending on local regulations.
  2. Alternatives recommended by authorities: Pest control authorities generally recommend using traps, poisons, or professional services for rodent control instead of mothballs.

Proper usage and safety precautions

If you choose to use mothballs for any purpose, it is important to follow guidelines for safe usage.

Guidelines for using mothballs safely

  1. Ventilation and placement: Place mothballs in well-ventilated areas, away from living spaces and sources of heat or flame.
  2. Storage and disposal: Store mothballs in sealed containers and dispose of them according to local regulations.

Signs of mothball poisoning and first aid measures

  • Recognize symptoms of mothball poisoning in humans and pets, such as difficulty breathing, vomiting, and seizures.
  • If you suspect mothball poisoning, seek medical or veterinary help immediately.

Tips for preventing accidental ingestion by children and pets

  • Keep mothballs out of reach of children and pets.
  • Use childproof containers and clearly label them to avoid confusion.

Alternative methods for keeping mice away

Natural repellents and DIY solutions

  1. Essential oils and spices: Peppermint, eucalyptus, and clove oils, as well as cayenne pepper, can be used as natural mouse repellents. However, they may need to be reapplied frequently to maintain their effectiveness.
  2. Predators and companion animals: Cats and certain dog breeds can help control rodent populations by hunting mice or acting as a deterrent.

Preventive measures and exclusion techniques

  1. Sealing entry points and holes: Identify and seal any cracks or holes in your home’s foundation, walls, and roof to prevent mice from entering.
  2. Proper sanitation and food storage: Keep your home clean and store food in sealed containers to reduce the availability of food sources for mice.

Professional pest control services

If you have a persistent mouse infestation, consider hiring a professional pest control service to assess the situation and recommend the most effective solutions.

Frequently Asked Questions

Let’s answer the most frequently asked questions about mothballs and mice.

1. Do mothballs repel mice safely indoors?

Mothballs may repel mice to some extent indoors, but they come with safety risks. Mothballs contain chemicals like naphthalene or paradichlorobenzene which release toxic fumes that can be harmful to humans and animals if inhaled. These fumes can cause respiratory issues, headaches, and nausea. Moreover, the effectiveness of mothballs in repelling mice is limited, as mice can adapt to the smell over time. It is generally advised to use safer and more effective methods to keep mice at bay, such as sealing entry points, maintaining cleanliness, using traps, or seeking professional pest control assistance.

2. Do moth balls keep mice away outdoors?

No, mothballs do not effectively keep mice away outdoors. While mothballs are known to repel certain pests like moths, their effectiveness in deterring mice is limited. Mice have a strong sense of smell, and although mothballs have a strong odor, it does not have a significant impact on mice. Additionally, mothballs are toxic and can pose a danger to outdoor wildlife, pets, and the environment. It is better to rely on alternative methods to deter mice outdoors, such as sealing off entry points, removing potential food sources, and using natural repellents like peppermint oil or ultrasonic devices.

3. What do mouse urine stains look like?

Mouse urine stains typically appear as small, dark smudges or spots on various surfaces. They may resemble tiny droplets, ranging in color from yellowish to brown or black. These stains are often seen on floors, walls, furniture, or near nesting areas. Mouse urine has a distinctive odor, which can help identify the presence of mice. It is important to address these stains promptly, as they can contribute to the spread of bacteria and disease. Regular cleaning and proper rodent control measures are crucial to maintain a healthy and hygienic environment.

4. How do mothballs work?

Mothballs work by slowly releasing toxic fumes that repel or kill moths and other fabric-damaging insects. They contain a chemical called naphthalene or sometimes paradichlorobenzene, which vaporizes at room temperature. When mothballs are placed in a sealed container or storage area, the fumes spread, creating a hostile environment for moths. These chemicals interfere with the moth’s ability to detect pheromones, making it difficult for them to find mates or food sources. The strong odor also repels moths, deterring them from infesting clothing or other susceptible items. It’s important to note that mothballs are toxic and should be used with caution, following proper instructions and safety precautions.

5. What keeps mice away permanently?

To keep mice away permanently, it is crucial to eliminate their entry points and create an environment that is unappealing to them. Start by sealing any cracks, holes, or gaps in the foundation, walls, and windows, denying them access. Maintaining cleanliness is vital: regularly clean the house to remove any food residues, crumbs, or spills that can attract mice. Store food in airtight containers, and use well-sealed garbage bins. Additionally, consider deterrents like peppermint oil, as the strong smell tends to repel mice. Setting up traps and regularly checking for signs of infestation can help address any potential issues promptly.


While mothballs may have some success in repelling mice in certain situations, their overall effectiveness is limited, and they come with significant health and environmental risks. It is generally better to consider alternative methods for controlling mice, such as using traps, natural repellents, or hiring a professional pest control service. By understanding the risks and benefits of various mouse control methods, homeowners can make informed decisions about how to keep their homes free from these unwanted pests.


  • Nathan Collins

    Having spent years working in the landscaping industry, Nathan Collins has cultivated a wealth of knowledge about the natural world. He is committed to helping others appreciate the beauty in their backyards, whether it's through identifying rare rocks and minerals or crafting the perfect landscape.

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