m0useanswered grow question 3 years ago I 2nd the motion of checking under the leaves, use a magnifying glass and look for egg shells or small eggs of mites.
This is what you looking for, its very small.
http://www.biobestgroup.com/public/uploads/images/news/tetranychus-urticae-adult-009.jpg
Soap and water or use a miteacide if it is mites.
Good Luck!