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urbana (Slabaugh), urban silverfish
Lepisma saccharina (Linnaeus), silverfish
Julian R. Yates III
Extension Urban Entomologist
College of Tropical Agriculture and Human Resources
University of Hawaii at Manoa
Immature and adult stages of L. saccharina consume primarily carbohydrates and protein; they prefer protein, however, and are cannibalistic, feeding on molted skins and dead and injured individuals. They are also fond of flour and starch and are sometimes found in cereal. Other articles susceptible to attack include muslin, starched collars and cuffs, lace, carpets, furs, and leather. C. urbana individuals have been observed feeding on animal and vegetable matter, including wheat flour. They appear to be extremely attracted to beef extract when it is spread as a paste on paper.
The silverfish is a primary pest of paper and paper products, especially those that contain starch, dextrin, casein, gum, and glue. In the laboratory, C. urbana preferred paper products such as cleansing tissue, onion skin, and cellophane, and ignored unprinted or printed newsprint, cardboard, and brown wrapping paper. Experiments demonstrated that it preferred highly refined papers over those containing a high level of mechanical pulp. It also fed on artificial silk and cotton, but did not touch wool or true silks. It preferred textiles of vegetable origin such as rayon, cotton, lisle, and-most of all-linen.
They are widely distributed and have been seen in Australia and other parts of the Pacific, in Japan and other parts of Asia, and in North America and Europe.
A silverfish infestation develops very slowly, and damage resulting from this pest can be easily identified. For example, the damaged edges of paper will be very irregular or notched, and the sizing, or coating, of the paper with be removed in an irregular pattern. With heavy infestations, irregular holes will be eaten through the paper. Book bindings will have tiny irregular scrapings. Silverfish feces, when present, are small, dark, and loose. Yellow stains, scales, and/or feces may also be evident on the textile being attacked.
Eggs are elliptical and about 1 mm long. When first laid, they are soft and white; they turn yellow and eventually brown after several hours. Eggs are laid singly or in batches of two to three, and are deposited in crevices or under objects. Under optimum conditions, an adult female lays an average of 100 eggs during her life span. Eggs hatch at temperatures ranging from 22ūC to 32ūC. Optimum temperature is about 22ūC. At this temperature the average incubation period is 43 days.
The first-instar nymph molts in 7 to 10 days, and each subsequent instar (stage between molts) takes about 2 to 3 weeks for development. Nymphs undergo six to seven molts.
A life cycle of 7 to 9 months has been observed that resulted in three to four generations every 2 years. These pests are long-lived and are capable of reproduction after 3.5 years at 22ūC. Adult females have been observed to alternately lay eggs and molt, and may molt as many as 50 times. Adult body length is about 12-19 mm.
They hide during the day and prefer to hide or rest in tight cracks or crevices. They will tend to travel some distance in search for food, but once a satisfactory food source is found, they remain close to it. They prefer room temperature areas and high relative humidity.
Remove potential food supplies by placing them in tightly sealed containers. Eliminate potential infestation sites by sealing cracks and crevices with putty or caulking. Change the physical environment of susceptible areas to discourage the start of an infestation or to control an existing infestation.
These pests prefer to hide in tight cracks and crevices, so an approved insecticide should be applied only to those areas as a spot treatment. Wide applications to other areas, such as shelf surfaces, will only contaminate your belongings and have very little effect on the silverfish. Consult your local pesticide supplier for recommended insecticidal products.
Ebeling, W. 1978. Urban entomology. Division of Agricultural Sciences, University of California, Berkeley.
Mallis, A. 1982. Handbook of pest control. Franzik & Foster Co., Cleveland, Ohio.
Morita, H. 1926. Some observations on the "Silverfish" (Lepisma Saccarina L.) (Thys.). Proceedings Hawaiian Entomological Society. 6(2):271-273.
Smith, Eric H. and Richard C. Whitman. 1992. NPCA Field Guide to Structural Pestsss. NPCA.
Zimmerman, E. C. 1948. Insects of Hawaii. Volume 2. University of Hawaii Press, Honolulu, Hawaii, pp. 29-38.