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Do Mothballs Repel Spiders?

Mothballs can be used to repel spiders, along with a variety of other small pests, but they shouldn't be. When used correctly, mothballs are ineffective against anything that isn't sealed in with them. When used incorrectly, in the open air, they do poison nearby spiders and moths. Unfortunately, they also potentially poison nearby people.

  1. Active Ingredients

    • The primary ingredients in mothballs consist of two powerful pesticides. These toxins are infused into mothballs and then released as a gas. The fumes released from these toxins are fatal to moths and other small invertebrates, including spiders. The two compounds are napthalene and its weaker counterpart, para-dichlorobenzene. The pesticide napthalene is three times as toxic as paradichlorobenzene.

    Recommended Use

    • Mothballs are designed to be sealed inside of airtight clothing containers, which then trap the fumes they produce. As these fumes build up within the container, they kill any insects or arachnids trapped inside. Mothballs can be used outside of a sealed container, and doing so will kill nearby spiders, crickets, silverfish and other pests, but this also exposes pets and family members to dangerous toxins. When used as directed, mothballs only affect what is sealed in with them.

    Dangers

    • Pets and small children may find mothballs left out in the open and eat or handle them. Both pesticides are associated with liver damage if ingested, and each has other distinct dangers of its own. Oral exposure or ingestion of para-dichlorobenzene also affects the blood and kidneys, and inhalation will irritate the eyes, skin and throat. Napthalene is associated with hemolytic anemia, as well as neurological damage in infants, regardless of whether it is inhaled, ingested or merely in contact with the skin.

    Alternatives

    • Capsaicin, which is what makes chili peppers hot, is an effective repellent. It works indoors and outside, and is primarily used in products designed only to repel instead of kill. Limonene, or d-Limonene, is a contact insecticide that will kill spiders and other small invertebrates, and has low oral and dermal toxicity to people. Extracts from neem tree seeds disrupt invertebrates' feeding and molting abilities, leaving them unable to fully mature and reproduce before they die. Neem has a low toxicity to people and reduces pests' presence over time by preventing future generations from being conceived.

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