In addition, infestations can start when eggs, nymphs or adults are brought into a house on infested cardboard boxes, cartons, furniture or similar items. Life history Silverfish and firebrats are long-lived insects. Development time from egg to adult takes anywhere from three months to three years for silverfish, whereas firebrats complete development from egg to adult in about four months. Adult silverfish and firebrats may continue to live for up to three years. This equals a potential lifespan of approximately six years for silverfish and three to four years for firebrats.
Adults continue to molt throughout the remainder of their lives.
Adults lay eggs in cracks and crevices near food sources. Depending on species, adults lay 5-50 eggs per clutch. These eggs hatch into nymphs, which look like small adults. They molt several times during the nymph and adult stages and have been observed to shed their skins more than 30 times a year. Development time from egg to adult varies between the four house-dwelling species and is summarized in Table 1.