Sometimes referred to as bristletails, silverfish are widely distributed in the United States and Canada. Other insects in the silverfish family are the firebrat, four-lined silverfish and the gray silverfish. Silverfish are primitive, wingless insects. The young are very much like the adults except for size. Adults are between ½” and ¾” (not including the tails). As they get older, distinguishing coloration develops. They range from silvery to gun-metal to almost black in colour. The bodies are teardrop shaped, tapering from head to rear. The eyes are small, compounded and wide-set. This species also has silver scales covering its body, giving it a silvery appearance.
Silverfish can live for long periods of time. They also molt continuously throughout their life, which may be up to eight years. Silverfish need to mate after each molt so that the female can lay fertile eggs. Females lay eggs in small batches of up to 50 depending on the species, but they generally lay less than 100 eggs during their life span. For this reason, infestations develop slowly. Populations do not build up rapidly. A large infestation in a structure indicates it has been infested for a long time.
Depending on the species, the habits and habitat of the silverfish may vary considerably. In general they are free living and can be found indoors or outdoors. They prefer warm temperatures and moisture (new construction, water pipes, etc.) The insects are active at night and move quickly.
In general, temperature and humidity control or lighting in certain areas will reduce populations. Residual sprays can be used in cracks and crevices and around baseboards, drawers, and furniture. Attics and crawl spaces may also be treated – remember the habits of the particular insect involved. Space sprays, fogs, and aerosols may help eliminate problem infestations. Dusts in wall voids and pipe chases give particularly long-term control.