For years we've had silverfish darting around our guest bathroom floor. I bought some silverfish traps (little cardboard boxes with sticky goo to ensnare them) and they helped, but didn't stop them. In 2017 I read that lavender oil is a good silverfish repellent. It's only [amazon_link asins='B00PYS7R7M' template='PriceLink' store='boingboing' marketplace='US' link_id='45821b01-58c1-4b72-95e5-f9356cc91bce'] for a small bottle on Amazon, so I decided to give it a try. I wetted the end of a Q-Tip with the oil and ran it around the perimeter of the bathroom floor, adding a little extra to a seam between the floor and the wall. It smelled nice and did not see a single silverfish for two weeks. I finally saw one, reapplied lavender oil on the perimeter of the floor, and it keep the little bastards aways for an even longer time. Now I hardly ever see them, and treat the floor every few months.
Image of silverfish by Christian Fischer, CC BY-SA 3.0, Link