About a week ago I found a mealy bug on my begonia. I've been thoroughly checking the plant since then and all I manage to find is miniscule white dots on the underside of the leaves. I assumed that the dots were mealy bugs but after reading on the internet that "white clumps" are what to look for when checking for mealy bugs, I'm not so sure that's what is on my plant. These dots are TINY, about the size of the period at the end of this sentence. So tiny that they probly wouldn't show up if I took a picture of them. But the dots are not a discoloring of the leaf because if I rub the leaf, the dots come off. Are these dots mealy bugs or somethin else?