Eggs hatch in two to eight weeks depending upon conditions. After three to four molts the nymphs develop adult coloration. Silverfish take three to four months to become sexually mature and may live for three to four years. Firebrat females lay up to 50 eggs in cracks and crevices. Because of the warmth, the eggs hatch in 12-13 days.
Nymphs are sexually mature in two to four months and full grown in a year.
Adults may live up to two years. Silverfish live in damp areas indoors or out, usually underneath boxes, boards, debris, etc. They may enter homes by being carried in on cardboard cartons, books, old papers or through house vents. They are active both day and night. Firebrats prefer very warm areas indoors where temperatures are above 90 F. Indoors they are usually found near heating units, fireplaces, and steam or hot water pipes if these areas are not too dry.