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	Silverfish & Firebrast

 Silverfish & Firebrast
by Dennis M. Ferraro Extension Educator Douglas/Sarpy Extension Unit

The term silverfish is used for the Thysanura and for any of the species within the order. However both silverfish and firebrats are in this group. Thysanurans have a distinct carrot-shaped body, short legs, long slender antennae and three tail-like appendages at the end of the body. They are wingless with scale-covered bodies which are about ½" long. Young (nymphs) resemble adults.
Firebrat - This insect is found throughout the world in warm climates. Found indoors in Nebraska in heated buildings, it is occasionally seen outdoors in the West and Southwest. Firebrats occur around ovens, bakeries, and other warm areas, as they prefer temperatures above 90°F. Firebrats may become serious pests in bakeries and in areas where starches are stored in warm temperatures, such as in warehouses.
The females deposit eggs in crevices. The numbers of eggs per hatch varies, with an average of 50. Eggs will hatch in 12-13 days under optimum conditions. Newly hatched nymphs are 1/8" long, white, and development is rapid. Firebrats can live up to two years at warm (90-98°F) temperatures. Firebrats can be killed when exposed to temperatures above 120°F for one hour or more. This can be an effective way to manage firebrats.
Silverfish - This pest is found indoors in the Midwest. It is found indoors in warm, humid areas such as basements.
The eggs are deposited in crevices or under objects singly or in groups of 2 or 3. The female deposits 1-3 eggs per day or at irregular intervals of up to several weeks depending on availability of food. Eggs hatch in 43 days at ( 72°F and in 19 days at 90°F, Adults may live up to 3-1/2 years, but most live 2 years under favorable conditions (72-80°, relative humidity of 75%-97%). Feeding habits of silverfish species are very similar. Once a source of food is located, silverfish remain in the vicinity. Silverfish feed on human foods, especially those containing starch or flour, as well as on paper, especially glazed-coated paper. They eat sizing on paper, as well as glue and paste. They may feed on wallpaper or the paste behind it, causing the wallpaper to become detached from the wall.
Materials such as writing paper, tissue, onion skin paper, and cellophane are preferred, as well as cotton, rayon, and other vegetable textiles. Newsprint, brown wrapping paper, and most cardboard are seldom eaten. Silverfish feed on bound volumes for the paper, the starch and sizing in the bindings, and then linen in some bookcovers. Stored papers, books, and other printed materials are especially susceptible. Sizing and glue are main attractants, especially if humidity is high. Silverfish seldom feed on wool and other animal-based textiles. Cereals may become infested due to the insects' preference for starches and flour. Silverfish can live for nearly a year without feeding.
Thresholds - Due to their small size and reclusive nature, silverfish are seldom seen. However, their damage may be significant if populations are high. The decision to intervene should be based on the amount of damage associated with the silverfish and the confirmation on an active infestation. Non-Chemical Control of Silverfish - Warm temperatures and high relative humidifies favor most silverfish species. Controlling or eliminating moisture in areas infested with silverfish can reduce populations. Air conditioners or dehumidifies placed in rooms where documents and books are stored can help to reduce humidity and temperature. Lower temperatures may also slow population growth by reducing rates of development and reproduction in silverfish.
Silverfish found in books and documents can be killed by exposure to microwave radiation. Olkowski in his book "Common-Sense Pest Control" recommends placing books in a microwave oven for a period of 30 to 60 seconds to kill silverfish. Caution should be used with books or documents containing color plates or in fragile condition.
Sealing cracks and crevices where silverfish hide and breed also reduces populations by reducing suitable habitat. If sealing or caulking is not possible, then cracks and crevices (particularly around bookcases) should be regularly vacuumed to remove silverfish. Good sanitation practices should be followed. All valuable paper products, books, and documents should be placed in tightly sealed containers and cabinets. If this is not possible, access to potential food sources should be limited by removal of food and harborage such as empty cardboard boxes and other waste paper. There is no information in literature on natural enemies of the Thysanura.
Chemical Controls of Firebrats And Silverfish - Several pesticides are recommended for use on firebrats and silverfish; however dusts and baits seem to give the best results. Dust pesticides and powder formulations should be applied only in cracks, crevices, attics, and other storage. These insects do not hunt for their food so bits must also be broadcasted in these locations as well as directed by the label.