The term silverfish is used for the Thysanura and for any of the species within the order. Thysanurans have a distinct carrot shaped body, short legs, long slender antennae and three tail-like appendages (anal cerci) at the end of the body. They are wingless with scale covered bodies which are about 1/2″ long. Nymphs resemble adults.
There are thirteen species of silverfish in the United States.
Mallis in the 1982 lists six species which may be pestiferous: They are the following,
- Firebrat, Thermometer domestica
- T. campbelli (Barhart)
- Silverfish, Lepisma sacchrina L.
- Four lined silverfish, Ctenolepisma quadriseriata (Luccas)
- Gray silverfish, C. longicaudata Escherich
- Acrotelsa collaris
This insect is found throughout the world in warm climates. Firebrats may become serious pests in bakeries and in areas where starches are stored at warm temperatures, such as in warehouses. The females deposit eggs in crevices.
Development is rapid, with only 1 day spent in the first instars and more time passing between successive instars. A firebrat may pass through 45 to 60 instars during its lifetime. The nymphs resemble adults.
Firebrats can be killed when exposed to temperatures above 120 F for one hour or more. Temperatures above 112 F and below 32 F kill nymphs. This can be an effective way to manage firebrats if it possible to elevate or reduce temperatures to these levels.
This species is found indoors in libraries. Little is known about its habits, but its life cycle resembles that of the firebrat.
This pest is common indoors on the East Coast, and is also found indoors in the Midwest and Pacific Coast. 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. 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 F, relative humidity of 75%- 97%). Silverfish may pass through up to 59 instars in their lifetimes.
This species is common on the East and West Coasts and in the Midwest. It lives indoors, often infesting attics, particularly if the roof is made of wooden shingles. It may be found outdoors in summer. Its life cycle is similar to that of the silverfish but not as limited by temperature and moisture.
This species occurs indoors in the South, Midwest, and southern California. It prefers drier areas than common silverfish, such as crawl spaces and attics, but may occur around water pipes in bathrooms.
It deposits its eggs in cracks in groups of 2-20. They hatch in about 60 days at room temperature. The nymphs are scale less when hatched; scales appear in the fourth instars. This species may live up to 5 years.
This species was recently introduced into Florida, probably from the tropics. Little is known of its life cycle but it may resemble that of silverfish.