The silverfish (Lepisma saccharina) is a wingless, scale-covered insect and a common household pest. These remnants of the dinosaur age are found throughout North America, and once they find a hospitable indoor environment they will wreak havoc, destroying clothing, furniture, wallpaper, books, and food.
Though they aren't dangerous to humans or pets, an infestation of silverfish can be repulsive and, in some cases, expensive. Luckily, the pests can often be eliminated, and further infestations prevented, with some simple steps.
Essential oils such as citrus, cedar, bay, and cinnamon are natural and safe silverfish repellants. You can make a simple repellant spray by mixing 10 drops of essential oil into three ounces of distilled water.
Soak cotton balls in this solution and then place them inside cupboards, the pantry, closets, underneath the sink, on bookshelves, or anywhere there is evidence of silverfish. Refresh the cotton balls as the fragrance dissipates.
Silverfish thrive in environments with high humidity. They often colonize in basements and crawlspaces and lurk in the bathtub or shower. Lowering humidity to a level below 75% not only makes the environment more comfortable to humans but also deters silverfish from nesting.
There are several things that you can do to lower humidity. Use a dehumidifier in the basement, laundry room, or bathroom. If you have central air conditioning, run it when the air seems clammy. Check the plumbing for leaks and have these repaired. Make sure that gutters and downspouts are in good repair and are shunting water away from the home’s foundation.
Although it is a pricy solution, encapsulating a crawlspace not only cuts down on humidity in the home but also seals cracks that allow insects access indoors. Many companies that perform crawlspace encapsulation also offer crawlspace dehumidifiers and sump pumps that keep the house dry.
Items such as books or clothing that have been damaged by silverfish, or that may be housing the insects, can be placed in plastic bags and put into the freezer for a few days. Freezing will kill any live insects and their eggs.
Silverfish snack on crumbs of food, dead skin, hair or pet fur, and dead insects. Vacuum the floors often to keep the availability of these snacks to a minimum. Silverfish can survive in vacuum bags, so after cleaning the infested area, seal up the vacuum bag in a plastic bag and discard it immediately.
Silverfish are both voracious and omnivorous, and the abundance of edible stuff available in most homes is magnetic to these pests. Newsprint, glossy magazine paper, the pages of books, and photographs are some of the high-starch, high-fiber foods favored by silverfish. To prevent issues, throw away newspapers and magazines when you're done with them. Replace cardboard storage boxes with plastic totes.
Protect photographs by storing albums in tight-fitting slipcases or sealed storage bins. Include a silica desiccant pack to reduce any trapped dampness inside. Framed photographs are also targets for silverfish, so check the frame to ensure it fits tightly against the photograph. If the backing is made of cardboard, replace it with foam core or fiberboard. For any particularly valuable or precious display pieces, it might be worth getting them professionally framed.
Flour, meal, grains, and kibble pet food are silverfish magnets. Throw away any bags of food in which you’ve seen insects or insect droppings. Keep flour, cereals, rice, pasta, and dry pet food in canisters with airtight lids.
If silverfish are eating your clothing, hang cedar strips in your closets. Wooden hangers made of cedar will repel both silverfish and clothing moths.
You can also sprinkle diatomaceous earth near the posts that hold the crossbars in the closets. This nontoxic ground mineral is made up of microscopic crystals with sharp edges that pierce the exoskeletons of the silverfish as they crawl through. This causes the insects to dehydrate and die.
Boric acid powder, available in most pharmacy isles, can be used in two homemade silverfish traps. The ingredient is toxic in very small doses to silverfish, and it's safe to use indoors.
To make a sticky trap, stir together one tablespoonful of boric acid powder with a quarter cup of white flour. Add just enough water to create a thick paste. Spread the paste onto index cards or small squares of corrugated cardboard. Place the traps in areas that are dark and damp, such as under the sink, in a dark corner of the laundry room, or inside the cupboards. The silverfish will be attracted to the flour and cardboard. Check the traps often and change them as needed.
Another simple option is the jar trap. Place a mixture of cracker crumbs, dried bread, and boric acid or diatomaceous earth into a Mason jar that is at least three inches tall. Cover the outside of the jar with masking tape, and put the jar in a dark area. The silverfish will crawl up the masking tape and enter the jar, but won't be able to get traction to crawl back out.
While do-it-yourself methods are effective in ridding a residence of silverfish, they are also time-consuming. It may be necessary to call in a professional for a severe infestation.
Pest control experts rely on two toxins to treat silverfish infestations: pyrethrin and propoxur. In liquid form, these toxins can be sprayed into cracks and crevices where silverfish hide, as well as into areas where the plumbing comes through the walls and floors. They should not be used in food preparation areas. Both toxins have immediate and residual effects. Although they don’t kill silverfish eggs, they will kill newly hatched insects for six weeks after the initial treatment.
Tell-tale signs of a silverfish infestation include: