It looks like spider mites to me, Although I could be wrong. Here is some info I gathered from the FAQ....
Spider Mites:
Signs of an Infestation:
Mites will first be noticed by the presence of small, discolored spots located near veins in the leaves. To see them, you will need the help of a 10X loupe, or a 30X Microscope. Mites use piercing mouthparts to suck sap. Mites will slow growth and attack the buds in advanced stages. The life cycle of the spider mite is closely tied to the temperature of the grow room; slow an infestation by keeping temp in the low 70?s.
Eliminating spider mites:
A ?No Pest strip? is very effective in eliminating them. Avid is a very effective systemic chemical control. A soapy spray will also keep their numbers in check (thoroughly coat underside of the leaves). Space plants out to minimize transfer movement between plants.
Good luck friend - BTF