DE is the best. Not only can insects not develop resistance to it, it's safe for you and your pets. You do have to be very careful applying it, because of the risk of inhaling it. When I had dogs, I developed a horrible tick infestation which was broken within one week of using DE. If you live in the south, you will always have cockroach control issues, and it nukes them as well.Third, Diatomaceous Earth will kill silverfish as well as other insects and even spiders. This white powder will essentially dehydrate the pests. You can sprinkle this around the home where the silverfish might be as well as use it in your garden. This is definitely a method of exterminating as opposed to repelling the silverfish.
Spiders are unfortunately collateral damage, but I rarely had any in the house.