If you right click and select 'View Image' you may be able to see the number of mites there are on this bottom board. There are tons, hundreds, maybe as many as a thousand. This is what I would expect to see on a bottom board from a hive that had died from varroa mites.
But this hive not dead.
This is the hive that I expected to die last fall due to an extremely high mite load. I remember inspecting this hive and seeing mites everywhere. I saw them crawling on bees, in cells with brood, crawling across the comb, everywhere. There were hundreds.
I expected this hive to die. But it didn't. Remember, this is a completely treatment free hive. No treatments ever. And yet it survives, even with a massive mite load. Admittedly, it's not doing great, but we shall see what happens. This is one of the reasons I let hives die on their own, to see exactly how much they can take and if they have what it takes to survive.