Mothballs are pesticides. When exposed to air, they eventually vaporize. They are intended to kill moths and moth larvae. In some states, Oregon for example, mothballs are registered pesticides and their use other than as directed on the label is illegal. The perception that mothballs could be a snake infestation remedy is loosely linked to what attracts snakes rather than what repels them.
The Food Chain
Many snakes prey on rodents as their main food source. Some also eat nestling birds and bird eggs, insects and lizards. Snakes are also prey. Some snakes eat other species of snakes. Birds of prey such as hawks and eagles eat snakes, and people kill snakes.
Snakes, like other forms of wildlife, are attracted to food and shelter. Snakes need a place to take up residence that is secure from temperature extremes, is damp and offers seclusion. When snakes are preparing to hibernate for winter, they may seek shelter under and inside of buildings including houses. If the house is home to mice, insects and pack-rats, snakes may enter where their senses direct them to seek food.
Nonlethal measures may help keep snakes from taking up residence in a home. One way is to eliminate as many access points as possible. Seal cracks, crevices and holes in exterior walls, foundations, around plumbing pipes where gaps in the wall may exist and also around connections to utilities. Installing one-quarter inch metal mesh called hardware cloth may seal openings, as will sheet metal with caulking as necessary. Well fitting screens should seal windows. Doors should have weather stripping fitted around exterior frames. Clearing away brush and debris from yards, keeping grass cut short and keeping mulch from piling deeply removes potential cover for snakes, offering them fewer locations to hide and search for food.
If grain-based feed such as wild bird food and pet food is stored in open containers, mice and rats may be attracted to the feed. Snakes are attracted to rodents. Therefore, covering and sealing feed can help discourage snakes from entering. Controlling insects also helps remove potential food sources that attract snakes.
The theory behind the use of mothballs as a snake repellent may be related to mothballs’ main ingredient, usually naphthalene. The odor of and fumes from naphthalene may have the effect of repelling rodents. Since snakes eat rodents, the absence of rodents may encourage snakes to seek food sources elsewhere.
It is important to remember that the label on the mothball package is a legal document with instructions for safe and approved use. Naphthalene may cause adverse health effects if mothballs are not used according to instructions. Naphthalene vapor exposure has symptoms that include difficulty in breathing, dizziness, headache and nausea. Mothballs should not be used anywhere where pets or children could eat them or be affected by their vapors.