You will want one lb. of dust per 800-1000 sq. Another very effective way is the use of baits in the attic or on the outside. It can be sprinkled out in a self contained one lb. bag, in all the areas you believe the silverfish are hiding. Being a bait, with a lure designed to attract the silverfish, you do have a better chance of eliminating the silverfish if you don't get to the habitat exactly, as they are lured to it as well. This type of aerosol is very helpful in bathrooms.
Adults are about one-half inch long.
They prefer temperatures around 100 degrees F and are found in boiler rooms and bakeries, around ovens, hot-water heaters and pipes. These insects follow pipelines from the basement to rooms on lower floors, living in bookcases, closet shelves, behind baseboards and behind window or door frames. A relative humidity of 70 percent to 80 percent is favorable because they do require some moisture. Firebrats are rarely found outdoors, while silverfish may be found outdoors. They may habitat all year long.