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SilverfishLespisma sacchrina (Linnaeus)
Silver to brown
Found throughout U.S.
What Do Silverfish Look Like?
Silverfish have no wings, but are able to run very fast. Adult silverfish have a body length of about ½-3/4” (12-19 mm) not including the tail. They have a flattened body and their shape is often compared to a teardrop, carrot or fish, tapering from head to rear and generally covered with scales. Silverfish are typically silvery or gun metal in color and have long, threadlike antennas. In addition, they have small compound eyes that are widely separated. Immature silverfish look similar to adults, except for size and their scales appear with the third or fourth molt.
Sign of an Infestation
Keep an eye out for feeding marks, although they may be irregular whether they are holes, notches along an edge, or surface etchings. Yellow stains, scales and/or feces (tiny black pepper-like pellets) may also be seen on infested materials.
People have noticed silverfish when they come down on ceiling soffits and/or drop from skylights and canister light fixtures in the ceiling, likely entering through shake roofs.
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Are silverfish harmful?
Silverfish are not considered a threat to humans, as they do not bite or spread disease.
Silverfish move fast and are good climbers. They can survive for weeks without food or water, but require a high humidity environment of 70 to 90 percent. Silverfish prefer areas of room temperature (70-85 degrees F/21-29 degrees C). They are nocturnal and prefer to hide or rest in tight cracks or crevices during the day. Silverfish can be found almost anywhere in a house including living rooms, bedrooms, bathrooms, attics, basements, garages and shake roofs. In fact, shake roofs are excellent breeding sites for silverfish during the warmer months, as they have an abundance of moisture, cellulose, starch and dead insects. From there, they can easily gain entrance and move down through the insulation to enter a home.
Silverfish are known to infest commercial structures such as offices, stores and libraries. They are often introduced into buildings via cardboard cartons of books and papers from an infested location. They will roam quite some distance while searching for food, but once they find a satisfactory food source, they remain close to it. Within structures, they will breed in a variety of areas, including wall voids, in/under the subflooring, attics, etc.
Silverfish usually feed on paper items, glue, clothing and food items, such as flour and rolled oats. They prefer proteins to carbohydrates and are cannibalistic — their favorite protein meals include dried beef and dead or injured of their kind.
The silverfish female lays about one to three eggs per day, placing them in cracks, under objects or left exposed. Developmental time is three to four months under favorable conditions of 72-90 degrees F and at least 50-75 percent relative humidity. Otherwise, it may require up to two to three years. The majority of silverfish live up to three years.
Silverfish are found throughout the U.S. and are typically seen in moist, humid areas in the home, such as bathrooms, basements, and attics.
Silverfish are mainly a nuisance pest. Indoors, they can cause property damage by chewing holes in clothing, upholstery and paper goods, such as wallpaper and books.