There is things you put plug into an outlet, lets off some high pitch noise or somthing??... I dont know how they work to be honest, but I paid about $7 at Cambodia Tire. They work. I store 2-2.5 years of fire wood in the basment and had lots of insects and rodents, geckos, all kinds of shit because of that. Plugged in 1 of those night light looking thngs and everything is gone. 2 cats and 2 dog dont seem to mind it, then go everywhere in the house still. Been 10+ years and littereally no bugs or spiders or nothing downstairs.