The answer to 'when to treat for silverfish' is that the best time to treat for silverfish is when you first notice their presence in your home. Silverfish are nocturnal insects that prefer damp, dark areas like bathrooms, basements, and kitchens. They feed on starches, sugars, and proteins, and can damage books, wallpaper, and clothing if left unchecked.
The most effective time to treat for silverfish is as soon as you spot them, as their populations can grow quickly. Treating early will help prevent further damage and infestation. Be sure to identify and eliminate any moisture sources that may be attracting them, and use a combination of prevention and targeted treatment methods for best results.