I found the thread interesting about what the activity around the hive entrance can tell you.
Now, here's my question. What can the crud on the bottom board tell you?
I have a Screened bottom board, and haven't noticed any mites on the insert. I do, however see a bunch of other stuff like wax bits, pollen balls, red specks, . . . etc. Can I infer anything? I guess I can infer that pollen is being collected. How about the wax bits? Bees being hatched?