Silverfish have flat, elongated bodies 1/4 to 1/2 inch long and are broad near the head, tapering toward the rear. They have a rather carrot shape to them. They are wingless insects, coveredwith scales and have two long, slender antennae at the head, accompanied by three antennae-like appendages at the rear. One of these points straight back, while the other two curve off to the sides.
The Silverfish adult is about 1/2 inch long with a uniform silvery or pearl-gray color. The four-lined silverfish is about 3/4 inch long and uniform light to dark gray. The young resemble adults except adults, except they are smaller (as one would expect). They will be adults within 3 months.

Silverfish normally live outdoors under rocks, bark, and leaf mold, in the nests of birds and mammals, and in ant and termite nest. They are also found in home. Being drawn to moisture, they are often found in kitchens, bathrooms, and basements. under sinks, stoves, and floor, and around water pipes, in damp cool places, around bookcases, windows, door frames, and closets, and just about about anywhere they can find a warm, humid place to live. The firebrat prefers hot, dark areas around furnaces and fire places, and insulation around hot water or heating pipes. They are active year around. Any paper left in a damp area is in danger of these bugs.
Female silverfish may lay over 100 white, oval eggs during a lifetime. Eggs are laid singly or two to three at a time in small groups in cracks and crevices, hatchin three to six weeks later. Their populations do not grow rapidly due to their slow development rate, so a largr population is indicative of a long term problem. They are generally found in sinks and bathtubs, where they fell looking for water and could not get out.