Voids where plumbing is located. Voids behind electrical outlets. Molding around windows and doorways. The attic, crawl space and basement. The soffits.
Silverfish can be very difficult to control, especially in those homes which have wood shake (shingle) roofs. Shakes hold moisture and permit surface molds to grow which serve as food for silverfish. Shake roofs are also very difficult to treat completely -- to reach all the areas where silverfish can possibly live. In addition, silverfish often live in the soffits and behind the fascia board behind gutters. Individual silverfish then invade the interior of the home from this "reservoir" site. Compounding the problem in attics is blown-in insulation that prevents a professional from safely venturing into the attic to look for silverfish harborages. A professional should be consulted when silverfish are a regular problem. Areas that may require treatment include: