Silverfish

While silverfish and firebrats cannot bite, nor do they carry or transmit diseases, they are quite often a nuisance simply by their presence and can damage certain materials. They are members of a primitive order of insects which have a teardrop/carrot/fish- shaped body and get the common name of bristletail because of their 3 long, bristle-like or tail-like appendages on the rear end of their body. Both silverfish and firebrats are found in the Kansas City area.

Silverfish and Firebrats

If items on your bookshelf have chewed-on pages and bindings, suspect the look–alike household pests silverfish and firebrats. Both insects have enzymes in their gut that digest cellulose. Thus they choose bookcases, closets, pantries and places where books, clothing, starch, or dry foods are available.

Silverfish and firebrats are nocturnal and hide during the day. If the object they are hiding beneath is moved, they will dart toward another secluded place. They come out at night to seek food and water. Both insects prefer dry food such as cereals, flour, pasta, and pet food; paper with glue or paste; sizing in paper including wallpaper; book bindings; and starch in clothing. Household dust and debris, dead insects, and certain fungi also are important sources of food. However, they can live for several months without nourishment.

Recognition

There are several species of silverfish which infest homes and other structures in this area. Adults of all species are slender, wingless, soft-bodied insects, taper gradually from front to rear, with 3 long, thin, tail-like appendages and 2 long, slender antennae. Knowing the difference between the species will often promptly lead an Augustine technician to the exact source of the problem. .

  1. The common silverfish, Lepisma saccharina, is shiny, silver or pearl gray, and about 1/2 inch long, not counting the long, very slender tails, although it can grow as long as 3/4 inch
  2. Gray Silverfish, Ctenolepisma longicaudata. The scales are uniformly gray; adult body length excluding tails about ¾ inch.
  3. The common firebrat, Thermobia domestica is shiny, a mottled gray or brown, and about 1/2 inch long.

 

Immature silverfish and firebrats are similar to adults in appearance, except for size.

If you see scales around or beneath damaged items, it is a good indication that these pests are the culprits. The scales are delicate, dustlike, and slightly incandescent in the light, and they stick to most surfaces.

Similar Groups

  1. Diplurans (order Diplura) have only 2 appendages at the end of abdomen and they lack compound eyes.
  2. Springtails (order Collembola) lack tails but usually have a forked appendage at end of abdomen.
  3. Other larval and wingless adults of insects with complete metamorphosis lack 3 bristle-like appendages on the abdomen.

 

Damage and Signs of Infestation

Feeding marks are irregular whether they are holes, notches along an edge, or surface etchings. Yellow stains, scales, and/or feces may be seen on infested materials.

Biology

Silverfish lay about 1-3 eggs per day, placing them in cracks, under objects, or left exposed. Egg hatch requires 72-90 F (22-32 C) and at least 50-75% relative humidity. Developmental time (egg to adult) is 3-4 months under favorable conditions, but may require up to 2-3 years otherwise. The majority live about 3 years. The most favorable conditions are 72-80 F (22-27 C) and 75-97% RH. The four-lined silverfish (C. lineata) produces the enzyme cellulase in its midgut and can therefore digest cellulose.

The gray silverfish (C. longicaudata) female lays her eggs in batches of 2-20, placing them in cracks. the first instar lacks setae (hairs) and scales, scales appear in the 4th instar, and genitalia in the 14th instar. Sexual maturity is reached in 2-3 years and it may molt 3-5 times per year for another 5 years. Cellulose-digesting bacteria and enzymes are found in its midgut.

Adult female firebrats begin laying eggs at about 1½ to 4½ months of age, under conditions of 90°F to 106 °F. Female firebrats can lay up to 195 eggs in a lifetime. Nymphs hatch after an incubation period of about two weeks. The complete life cycle of a firebrat may last only 2 to 4 months, resulting in several generations each year.

Habits

All these silverfish species hide during the day and prefer to hide or rest in tight cracks or crevices. They can be found almost anywhere in a house including living rooms, bedrooms, bathrooms, attics, basements, and garages. Silverfish infest commercial structures such as offices, stores, and libraries. They tend to roam quite some distance while searching for food, but once they find a satisfactory food source, they remain close to it. Within structures, they can be breeding in a variety of areas, including wall voids, in/under the subflooring, attics, etc.

Silverfish can survive for weeks without food or water. The common silverfish (Lepisma saccharina) prefer areas of room temperature (70-85F/21-29C) and high relative humidity (70-100%). They prefer proteins to carbohydrates and are cannibalistic. They are often introduced into buildings via cardboard cartons of books and papers from an infested location. They are pests of paper, particularly of glazed paper and paper with sizing, wallpaper and wallpaper paste, etc. Silverfish eat proteins such as dried beef and dead or injured of their kind.

The gray silverfish can be found throughout a building from basement to attic, but are not found outdoors. Often heat ducts and ventilators from the basement serve as avenues for widespread infestation. They survive well in both dry and moist conditions. Gray silverfish feed on carbohydrates and proteins of both plant and animal origin. They are fond of wheat flour and beef extract, especially when used as a paste on paper. Gray silverfish prefer papers of high chemical pulp content such as onion skin, cleansing tissue, cellophane (almost pure cellulose), etc., as opposed to newsprint, cardboard, and brown wrapping paper. They readily eat artificial silk, linen, rayon, lisle (long-strand cotton), and cotton, but not wools or true/natural silks; linen is most preferred.

As their common names implies, firebrats thrive best in very warm, dry places with a relative humidity as low as 30% and temperatures above 90°F, with the optimum being 98° to 102°F. However, they can survive at temperatures ranging from freezing to well above 100°F. You can find them around ovens, heating units, fireplaces, hot water pipes, attics during the summer, and the furnace during winter.

Control

The key to control is identification which directs one to the preferred areas of habitation and food materials as outlined above. Identification is followed by a thorough inspection of preferred habitat areas and where appropriate food materials are present.

Once the infestation(s) is found, thorough housekeeping may be followed by selection of an appropriate pesticide formulation. Many infestations are very localized and environmental modification can greatly enhance control - e.g. controlling or eliminating moisture by repairing leaking pipes, sealing up easily accessible cracks and crevices, removal of potential food sources, etc.

Augustine Exterminators’ technicians are extremely well-versed in the management of silverfish problems. Call 913-362-4399 to set up an appointment for inspection and control measures.