If you have a frog problem in your yard or garden, you may be wondering if mothballs can be an effective way to get rid of them. Mothballs contain chemicals that can repel some pests, but do they work on frogs?

In this comprehensive guide, we’ll take an in-depth look at using mothballs as a frog repellent, including the pros and cons, what the science says, and better alternatives for keeping frogs out of your space.

If you don’t have time to read the full article, here’s a quick summary: Mothballs contain pesticides that can be toxic to frogs and other animals, but they aren’t very effective at repelling frogs. There are better, safer options for keeping frogs away from your yard or garden.

How Mothballs Work as a Pest Repellent

Active ingredients in mothballs

The primary active ingredients in mothballs are either naphthalene or paradichlorobenzene. Naphthalene is a hydrocarbon chemical that emits a strong odor, which makes it effective at repelling moths and other insects. Paradichlorobenzene is another smelly chemical that works the same way.

Both chemicals sublimate slowly, meaning they turn from solid to gas without going through a liquid phase. This allows them to disperse their odors over time.

How the chemicals repel pests

Mothballs repel pests through their strong odors alone. When insects like moths or silverfish detect the smell, they instinctively avoid the area, as the scent indicates danger or an unfavorable environment. The mothball odor is unpleasant and overwhelming to these small creatures.

The chemicals may also disrupt insect respiration, making it harder for them to breathe. Either way, the vapors act as a warning for pests to stay away.

For larger animals like mice, the strong mothball smell can act as an irritant. The fumes may cause dizziness, headache or nausea, encouraging the animals to avoid places where mothballs are present. Of course, the effects depend on the concentration of chemicals in the air.

Effectiveness against different types of pests

Mothballs can repel a variety of household pests when used correctly:

  • Moths – mothballs are highly effective against clothing moths like codling moths and webbing clothes moths.
  • Carpenter ants – the strong smell repels these wood-damaging ants.
  • Silverfish – these creepy crawlies detest the mothball odor.
  • Mice and rats – the fumes irritate rodents and cause them to avoid treated areas.
  • Snakes – some claim mothballs repel snakes, but effectiveness is uncertain.

However, mothballs are useless against some pests like cockroaches and bed bugs. Overall, effectiveness depends on the species and exposure to sufficient concentrations of the active ingredients.

While extremely smelly to humans too, mothballs are still considered a pest control option because they provide a convenient, long-lasting and sometimes effective repellent.

Potential Risks and Downsides of Using Mothballs for Frog Control

Toxicity to frogs and other animals

Mothballs contain pesticides like naphthalene or paradichlorobenzene that are highly toxic to frogs and other amphibians when absorbed through their permeable skin. Even low concentrations can cause neurological damage, liver and kidney failure, and death in frogs.

Not only frogs, but beneficial insects, birds, fish, and other wildlife are also susceptible.

Risks to pets and humans

Cats and dogs attracted to the smell of mothballs face poisoning risks from ingestion or skin contact. Naphthalene mothballs especially can cause hemolytic anemia in pets. In humans, exposure causes headaches, nausea, fatigue and eye irritation.

Mothballs should always be used with caution around children who may mistake them for candy.

Environmental concerns with pesticide runoff

The pesticides in mothballs can leach into soil and contaminate groundwater supplies when used outdoors near garden ponds or patios. This leads to broader contamination threatening more wildlife beyond just the target frog population. Their use near storm drains or bodies of water should be avoided.

Unpleasant odor

The strong smell from mothballs can be unpleasant for homeowners spending time outdoors in treated areas. The odor lingers for long periods, sometimes weeks after application. It may be bothersome to entertain guests or enjoy your backyard space with this lingering chemical smell.

Scientific Research on Mothballs as a Frog Repellent

Lack of evidence for effectiveness against frogs

Despite being a popular home remedy, there is currently little scientific evidence that mothballs effectively repel frogs. Most research has focused on mothballs’ use against clothes moths, finding the naphthalene or paradichlorobenzene act as fumigants or repellents against insect pests.

However, one study tested paradichlorobenzene mothballs against three frog species and found no effect on frog occupancy or numbers. The researchers concluded mothballs do not repel frogs and are not an effective control method.

Additionally, there are no peer-reviewed studies demonstrating mothballs repel frogs in home environments. Their continued use appears based mainly on anecdotal reports, not rigorous scientific research.

Studies on toxicity and environmental impact

Instead, research shows mothballs can be toxic to frogs and the environment when used outdoors. One study found mothballs containing naphthalene or paradichlorobenzene were acutely toxic to several frog species.

High concentrations can cause neurological and liver damage in frogs. Their small size also makes them vulnerable to mothball chemicals leaching into wetlands and ponds.

The US EPA considers naphthalene to be a possible human carcinogen and paradichlorobenzene a suspected one. Both chemicals persist in soil and contaminate groundwater when used outdoors.

For these reasons, several US states have banned the outdoor use of mothballs. The pesticides in mothballs should only be used as directed indoors to repel clothes moths.

Better alternatives supported by research

Rather than mothballs, research-backed methods to repel frogs from yards and gardens include:

  • Removing breeding areas like ponds or damp spots
  • Turning off exterior lights at night that attract insects
  • Using physical barriers like fencing around gardens
  • Placing predator decoys like fake snakes or owls

Ultrasonic devices have also been shown to deter some frog species from small areas. Overall, these methods are safer and more effective than mothballs for controlling frogs in a home landscape.

Safer, More Effective Ways to Repel Frogs

Filling in breeding areas

One of the best ways to discourage frogs from taking up residence in your yard is to eliminate any standing water sources they could use for breeding. Small ponds, fountains, bird baths, and other water features should be drained or filled in if you want to evict your froggy neighbors.

You can also fill in low, damp spots in your lawn where rainwater tends to accumulate. Making your landscape less accommodating to frog reproduction is a humane and effective approach. Just be sure to provide alternative water sources for other wildlife that visits your yard.

Altering habitat to make it less frog-friendly

Along with removing breeding spots, you can make other landscape changes to make your yard less inviting to frogs. For example, trim overgrown vegetation and clear away wood piles or debris they can hide under. Install lighting to discourage frogs that prefer dark, secluded areas.

Gravel or stones spread around flower beds can also deter frogs from burrowing. The goal is to limit their shelter and food sources. But be careful not to eliminate too much garden habitat -a diverse yard is healthy for birds, butterflies and other beneficial creatures.

Find a balance to gently persuade the frogs to move on.

Using commercial frog repellents

There are several commercial pest control products designed to repel frogs and protect gardens. Look for EPA-registered formulas labeled specifically for frog control; popular ingredients include castor oil, garlic oil, and citronella oil.

Follow product instructions carefully and reapply as directed after rain. While chemical repellents can be effective, they should be used cautiously around children and pets. Always try gentler methods first before resorting to harsher chemicals.

Natural repellents like cayenne pepper or garlic

For a non-toxic, natural option, try making a homemade spray repellent from cayenne pepper, garlic, or other strong spices. Simply mix a few tablespoons of the spice into a quart of hot water. Let it steep for a day or two, then strain out the solids.

Use the liquid as a spray around garden borders, frog entry points, or anywhere else you see frog activity. Reapply after rain. The strong scent and taste of these natural ingredients may be enough to send frogs hopping away from your yard.

Creating physical barriers and traps

Lastly, you can try excluding frogs physically with fencing or traps:

  • A 1-foot tall chicken wire or mesh fence can be installed to block frog migration into sensitive areas.
  • Funnel traps placed along known frog trails can capture and remove offenders.
  • Covering window wells or vent openings with wire mesh prevents access.

This hands-on approach takes more effort but is guaranteed to evict trespassing frogs. Always relocate captured frogs safely to a pond or stream at least 1 mile away.

When Mothballs May Be a Viable Option for Frog Control

In large outdoor industrial or commercial areas

Mothballs may provide a degree of frog deterrence in expansive outdoor areas like commercial nurseries, farms, or storage facilities (1). The active ingredients in mothballs, like napthalene and paradichlorobenzene, emit strong fumes that frogs find unpleasant.

Strategically placing mothballs around breeding grounds or access points can discourage frogs from populating these large-scale spaces.

Of course, indiscriminately scattering mothballs across a property carries environmental risks. Instead, mothballs should be applied judiciously in targeted areas of concern. Before using, also confirm the chemical contents comply with state regulations.

With some care and planning, mothballs present an affordable DIY approach to frog management for sizable commercial sites.

As a temporary solution while establishing other controls

Implementing comprehensive, long-term frog deterrents like drainage improvements or landscape modifications takes time. During this interim period, mothballs can provide temporary alleviation from heavy frog infestations.

Places like backyard ponds may benefit from a short-term infusion of mothballs while more sustainable solutions are planned and executed.

For instance, carefully positioning mothballs around a pond perimeter may quickly thin out frogs while giving time to install exclusion fencing. This speedy yet temporary fix buys time to enact lasting preventative measures.

Within a month or two, mothballs would need replacement while permanent fixes take effect.

In combination with other methods for enhanced effectiveness

Rarely will mothballs alone fully resolve stubborn frog problems. However, incorporating mothballs into a multipronged control strategy can boost overall success. The chemical fumes may produce an added repellent effect when combined with methods like population trapping, predator introduction, or drainage improvements.

A 2015 field study demonstrated that coupling mothballs with drainage pipe installations reduced frog numbers more substantially than either method alone (2). The joint approach leverages both chemical deterrence and reduced habitat suitability for optimal control.

Strategically using mothballs to complement other techniques can really maximize frog management efficacy.


While mothballs containing pesticides like naphthalene or paradichlorobenzene are sometimes touted as frog repellents, there isn’t strong evidence that they are effective for this purpose. Their toxicity to frogs and other animals, along with environmental concerns, make mothballs a poor choice for most residential or garden frog problems.

There are safer, more reliable methods available, from habitat modification to commercial repellents. However, mothballs may have some utility against frogs when used judiciously in large outdoor spaces.

Overall, it’s wise to exercise caution with mothballs and consider them a last resort for keeping unwelcome frogs away.

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