How do you catch silverfish? With silver bait!
The goofiest of all pests, silverfish are very hard and very easy to kill. They look like they have lots of legs. They have six. They show up in sinks and bath tubs with no way out. Or they show up all over the house with no pattern to the sightings.
Silverfish breed in sewer lines, and have no trouble working back through the lines to enter sinks or baths from the drain. They are present outside, and can invade from low entry points, or can climb the exterior walls of the house, and enter through attic vents. (Their cousins, firebrats, look like them and like to dwell under the roof shingles.) They like to eat the material some boxes are made of, and will dwell in the box in the attic, riding with the box when it is retrieved.
Finding the source is key to killing them. Those goofy questions we ask are important.