How does one "get" mites?

This summer I pollinated our melon fields and another beekeeper pollinated an adjacent field of melons, our pallets of hives were 25 feet apart. Since we get along pretty well he told me that since bees coming back near dusk will sometimes go to the nearest hive and hole up I should seriously consider treating for mites since his hives were infested. Three weeks ago I did an oxalic acid treatment and each treated hive has dropped thousands of mites. Doesn't matter how you get mites, you're going to get them. What are you going to do to control them?

I'm starting my third year as a beekeeper, and chemical free. In year 1, I didn't see mites. Started foundationless and I think the life cycle curves just make the first year a pass year in a lot of ways. The mite population can't bloom until the bees establish, blah blah. Year 2 though - yeah, had 'em. Have 'em. Hoping to keep the levels low.

I bought Freeman oil traps. It's technically for small hive beetle (and quite effective) but also gives you a good sense of mite loads, since they fall in and drown too, and you can pull it out and take a look. I dust with powdered sugar which seems to help. We'll see. I'm pretty happy to have gotten the bees into year 3. Hopefully it's a good run I can help keep going.