Yeah, scale can travel, but i don't know how far. When they first hatch they are crawlers. Ants will also spread scale as it produces honeydew, like aphids. Anyhow, i've been battling scale mess on my male kiwi and my contorted mulberry for many years. The only thing that seems to help is to spray with superfine oil (dormant oil or summer oil- mine is both depending on how you dilute it). It's supposed to be safe for harvestables. If i actually did several applications in one year i'd probably manage to actually lick it for good but the best i can do is 1 or 2 apps., so i still fight. I tend to hit it when dormant and in spring when i notice the white fuzzy crawlers (about now). That's the only solution i've ever found to be effective for scale on my outdoor or houseplants. Obviously, scraping it off with alcohol, which is tried & true advice, won't work on this level. Just spraying with alcohol isn't effective in my experience. Good luck!!